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THE  UNIVERSITY 


OF  ILLINOIS 
LIBRARY 

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GEOLOGY 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  DIRECTOR 


BULLETINS 

Nos.  447-450 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 
1911 


4^^'  ^ 0 Dro^'PTirrnnoo 


CONTENTS 


Geological  Survey  bulletin  447;  Mineral  resources  of  Johnstown,  Pa.,  and  vicinity. 
Same  448;  Geology  and  mineral  resources  of  Nizina  district,  Alaska. 

Same  449;  Geologic  reconnaissance  in  southeastern  Seward  Peninsula  and 
Norton  Bay-Nulato  region,  Alaska. 

Same  450;  Mineral  resources  of  Llano-Burnet  region,  Texas. 


iii 


Digitized  by  the  Internet  Archive 
in  2016 


https://archive.org/details/mineralresorceso4474phal 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


Bulletin  447 


MINERAL  RESOURCES 

OF 

JOHNSTOWN,  PENNSYLVANIA 
AND  VICINITY 

BY 

W.  C.  PHALEN 

AND 

LAWRENCE  MARTIN 


SURVEYED  IN  COOPERATION  WITH  THE 
TOPOGRAPHIC  AND  GEOLOGIC  SURVEY  COMMISSION  OF  PENNSYLVANIA 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

1911 


CONTENTS, 


Page. 

Introduction 9 

Geography 9 

Location 9 

Commercial  geography 9 

Topography 10 

Relief 10 

Surveys 11 

Triangulation 11 

Spirit  leveling 13 

Stratigraphy 14 

General  statement 14 

Quaternary  system 15 

Recent  river  deposits  (alluvium) 15 

Pleistocene  deposits 15 

Carboniferous  system 16 

Pennsylvanian  series 16 

Conemaugh  formation 16 

General  character 16 

Detailed  description 18 

Wilmore  sandstone  member 18 

Summerhill  sandstone  member 18 

Morgantown  (“Ebensburg”)  sandstone  member 19 

Harlem  (?)  coal 19 

Red  shale 19 

Saltsburg  sandstone  member 19 

Buffalo  sandstone  member 20 

Gallitzin  coal 20 

Lower  red  shales 20 

Mahoning  sandstone  member 20 

Allegheny  formation 22 

General  character 22 

Detailed  description 25 

Upper  Freeport  coal 25 

Upper  Freeport  limestone  member 25 

Bolivar  clay  member 25 

Butler  sandstone  member 25 

Lower  Freeport  coal 25 

Lower  Freeport  limestone  member 25 

Upper  Kittanning  (C7)  coal 25 

Johnstown  limestone  member 26 

Coals  between  Upper  and  Lower  Kittanning  coals 26 

Lower  Kittanning  coal 27 

Lower  Kittanning  clay  member 27 

Kittanning  sandstone  member 27 

Brook ville  and  Clarion  coals 27 

Pottsville  formation 27 


3 


4 


CONTENTS. 


Stratigraphy — Continued.  Page. 

Carboniferous  system — Continued. 

Mississippian  series 28 

Mauch  Chunk  shale 28 

Pocono  formation 29 

Devonian  system , 29 

Catskill  formation 29 

Structure 30 

Mode  of  representation 30 

Structure  in  the  Johnstown  quadrangle 31 

General  statement 31 

Detailed  description 32 

Wilmore  syncline 32 

Viaduct  anticline 33 

Johnstown  basin 33 

Laurel  Ridge  anticline 33 

Barnesboro  or  Westover  syncline 34 

Minor  structures 34 

Mineral  resources 35 

Introduction 35 

Coal 35 

General  description 35 

Upper  Freeport  coal 35 

Lower  Freeport  coal 35 

Upper  Kittanning  (C7)  coal 35 

Lower  Kittanning  (Miller)  coal 36 

Character  and  importance 36 

Coking  tests 38 

Miscellaneous  tests 39 

Lower  Allegheny  coals 7 39 

Composition  of  the  coals 40 

Description  by  districts 42 

Johnstown  district 42 

Extent 42 

Conemaugh  coals 43 

Character  and  distribution 43 

Gallitzin  coal 43 

Mahoning  coal 43 

Allegheny  coals 44 

Geologic  position 44 

Upper  Freeport  coal 48 

Name  and  position 48 

Extent  and  development 49 

Chemical  character 49 

Occurrence  and  physical  character 49 

Lower  Freeport  coal 51 

Name  and  position 51 

Extent  and  development 51 

Chemical  character 51 

Occurrence  and  physical  character 52 

Upper  Kittanning  coal 52 

Name  and  position 52 

Extent  and  development 53 


CONTENTS. 


5 


Mineral  resources — Continued.  Page- 

Coal — Continued . 

Description  by  districts — Continued. 

Johnstown  district — Continued. 

Allegheny  coals — Continued. 

Upper  Kittanning  coal — Continued. 


Chemical  character 54 

Occurrence  and  physical  character 56 

Middle  Kittanning  coal 56 

Lower  Kittanning  coal 57 

Name  and  position 57 

Extent  and  development 57 

Chemical  character 58 

Occurrence  and  physical  character 58 

Lower  coals 60 

Pottsville  coals 61 

South  Fork-Mineral  Point  district 61 

Extent * 61 

Geologic  position  of  coals 62 

Conemaugh  coals 62 

Coal  near  Summerhill 62 

Gallitzin  coal 64 

Allegheny  coals 64 

Upper  Freeport  coal , 64 

Name  and  position 64 

Extent  and  development 65 

Chemical  character 65 

Occurrence  and  physical  character 66 

Lower  Freeport  coal 67 

Upper  Kittanning  (Cement)  coal 67 

Name  and  position 67 

Extent  and  development 67 

Chemical  character 67 

Occurrence  and  physical  character 68 

Lower  Kittanning  (Miller)  coal 69 

Name  and  position 69 

Extent  and  development 69 

Chemical  character 69 

Steaming  tests 70 

Coking  tests 72 

Cupola  tests 73 

Producer-gas  tests 76 

Occurrence  and  physical  character 76 

Lower  Allegheny  coals 77 

Pottsville  coals 78 

Blacklick  Creek  district 78 

Extent : 78 

Geologic  position  of  coals 79 

Allegheny  coals 80 

Lower  Freeport  (D)  coal 80 

Name  and  position 80 

Extent  and  development 81 

Occurrence  and  physical  character 81 


6 


CONTENTS. 


Mineral  resources — Continued.  Page. 

Coal — Continued . 

Description  by  districts — Continued. 

Blacklick  Creek  district — Continued. 

Allegheny  coals — Continued. 

Middle  Kittanning  (C)  coal 82 

Lower  Kittanning  (B)  coal 82 

Name  and  position 82 

Extent  and  development 83 

Chemical  character 83 

Steaming  tests 83 

Coking  tests 85 

Producer-gas  test 86 

Washing  tests 86 

Briquetting  tests 87 

Occurrence  and  physical  character 88 

Lower  Allegheny  coals 89 

Windber  district 91 

Extent 91 

Geologic  position  of  the  coals 91 

Allegheny  coals 92 

Upper  Freeport  (E)  coal 92 

Lower  Freeport  (D)  coal 93 

Upper  Kittanning  (C')  coal 93 

Middle  Kittanning  (C)  coal 94 

Lower  Kittanning  (Miller  or  B)  coal 94 

Name  and  position 94 

Extent  and  development 94 

Chemical  character 95 

Occurrence  and  physical  character 95 

Lower  Allegheny  coals 95 

Conemaugh  Furnace  district 96 

Extent 96 

Allegheny  coals 96 

Upper  coals 96 

Lower  Kittanning  (B)  coal 97 

Extent  and  development 97 

Chemical  character 97 

Steaming  tests 98 

Coking  tests 98 

Washing  tests 99 

Briquetting  tests 99 

Occurrence  and  physical  character 101 

Coal  mining 102 

Room  and  pillar  system 102 

General  description 102 

Ventilation 104 

Drainage 104 

Haulage 104 

Mining  methods 105 

Long  wall  system 105 

Literature 113 


CONTENTS. 


7 


Mineral  resources — Continued.  Pa8e- 

Clay  and  shale - 113 

Mode  of  treatment 113 

General  description 113 

Flint  clays 113 

Plastic  clays 114 

Shales 115 

Description  by  districts 115 

Johnstown  district 115 

Flint  clays 115 

Plastic  clay 117 

Shales 119 

South  Fork  district 121 

Flint  clays 121 

Plastic  clay 123 

Shales 123 

Blacklick  Creek  district 124 

Flint  clay 124 

Plastic  clay 125 

Miscellaneous  localities 125 

Production 125 

Brick  industry 126 

Limestone  and  cement  materials 126 

Extent 126 

Upper  Freeport  limestone  member 126 

Lower  Freeport  limestone  member 126 

Johnstown  limestone  member 127 

Building  stone,  paving  blocks,  and  concrete  materials 129 

Glass  sand 131 

Iron  ores 132 

History 132 

Johnstown  ore  bed 132 

Extent 132 

Character  of  the  ore 133 

Physical  features  of  the  bed 134 

Water  resources 136 

Index 137 


ILLUSTRATIONS. 


Page. 

Plate  I.  Economic  and  structural  map  of  the  Johnstown  quadrangle,  Penn- 
sylvania  In  pocket. 

II.  Key  map  showing  the  location  of  the  Johnstown  quadrangle  with 

reference  to  the  entire  Appalachian  coal  field 9 

III.  A,  South  Fork  and  washed  away  dam;  B,  Sandstone  near  base  of 

Conemaugh  formation  near  Johnstown 20 

IV.  A,  Exposure  of  Lower  Freeport  coal  on  Stony  Creek  near  trolley 

bridge,  B,  Country  bank  of  the  better  class  on  the  Upper  Kit- 
tanning coal  near  Mineral  Point. 24 


8 


ILLUSTRATIONS. 


Page 

Plate  V.  A,  Typical  exposure  of  Mauch  Chunk  shale  at  the  viaduct  between 
South  Fork  and  Mineral  Point;  B,  Shale  quarry  of  B.  H.  Campbell, 

north  of  Sheridan,  at  the  Mercer  horizon 28 

VI.  A,  Detailed  structure  of  the  Loyalhanna  limestone;  B,  Loyalhanna 
limestone  (top  member  of  Pocono  formation)  at  summit  of  Ebens- 

burg  (Viaduct)  anticline,  Mineral  Point 28 

VII.  A,  Exposure  of  Upper  Kittanning  coal  and  Johnstown  limestone 
member  on  Stony  Creek,  near  mine  of  Valley  Coal  and  Stone  Com- 
pany; B,  Upper  Freeport  coal  and  overlying  shales  and  base  of 
Mahoning  sandstone  at  the  south  portal  of  the  Baltimore  and  Ohio 

Railroad  tunnel,  Stony  Creek 48 

Figure  1.  Sketch  map  showing  location  of  triangulation  stations  on  which 

survey  of  Johnstown  quadrangle  is  based 11 

2.  Skeleton  sections  showing  coals  in  Allegheny  formation  and  the 

intervals  between  them 24 

3.  Sketch  showing  the  great  irregularity  in  detail  of  the  structure  in 

parts  of  the  Johnstown  quadrangle  and  the  marked  regularity  in 
detail  in  other  parts 31 

4.  Sections  of  the  Upper  Freeport  (E  or  Coke  Yard)  coal  in  the  Johns- 

town district 50 

5.  Sections  of  the  Lower  Freeport  (D  or  Limestone)  coal  in  the  Johns- 

town district 52 

6.  Sections  of  Upper  Kittanning  (O'  or  Cement)  coal  in  the  Johnstown 

district 55 

7.  Sections  of  the  Lower  Kittanning  (Miller  or  B coal)  in  the  Johns- 

town district. . . : 59 

8.  Section  of  Clarion  (A7)  coal  in  the  Johnstown  district 61 

9.  Sections  of  Upper  Freeport  (E  or  Lemon)  coal  near  South  Fork 66 

10.  Sections  of  Upper  Freeport  coal  along  the  southeastern  margin  of 

the  Wilmore  Basin 66 

11.  Sections  of  Upper  Kittanning  (Cement  or  C/)  coal  in  South  Fork- 

Mineral  Point  district 68 

12.  Sections  of  Lower  Kittanning  (Miller  or  B)  coal  in  South  Fork- 

Mineral  Point  district 77 

13.  Section  of  the  Brookville  (A)  coal  at  mine  of  J.  H.  Wickes,  South 

Fork . 78 

14.  Sections  of  Lower  Freeport  (D)  coal  along  Blacklick  Creek 81 

15.  Sections  of  Lower  Kittanning  (Miller  or  B)  coal  in  the  Blacklick 

Creek  district 89 

16.  Sections  of  Upper  Kittanning  (Cement  or  CO  coal  in  the  Windber 

district 93 

17.  Sections  of  Lower  Kittanning  (Miller  or  B)  coal  in  the  Windber 

district 95 

18.  Sections  of  Lower  Kittanning  (Miller  or  B)  coal  in  Conemaugh 

Furnace  district 101 

19.  Diagram  illustrating  the  room  and  pillar  method  of  mining  in  the 

Johnstown  quadrangle 103 

20.  Plan  showing  long- wall  method  of  mining  as  employed  at  Vinton 

collieries  Nos.  1 and  3,  Vintondale 106 

21.  Plan  of  workings,  single  long- wall  conveyor  system 107 

22.  Plan  of  workings,  triple  long- wall  conveyor  system 108 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  447  PLATE  II 


KEY  MAP  SHOWING  LOCATION  OF  THE  JOHNSTOWN  QUADRANGLE  WITH  REFERENCE  TO  THE 

ENTIRE  APPALACHIAN  COAL  FIELD. 


MINERAL  RESOURCES  OF  JOHNSTOWN,  PENNSYLVANIA, 

AND  VICINITY. 


By  W.  C.  Phalen  and  Lawrence  Martin. 


INTRODUCTION. 

This  report  is  one  of  a number  of  bulletins  and  geologic  folios 
containing  the  results  of  geologic  investigations  carried  on  by  the 
United  States  Geological  Survey  in  cooperation  with  the  Topographic 
and  Geologic  Survey  Commission  of  Pennsylvania.  Several  papers 
based  on  this  work,  for  which  the  State  paid  one-half  the  cost,  have 
been  or  will  soon  be  published  by  the  State;  others  are  in  prepara- 
tion for  publication  by  the  United  States  Geological  Survey. 

The  field  work  on  which  this  bulletin  is  based  was  done  in  the 
summer  of  1906  by  W.  C.  Phalen,  assisted  by  Lawrence  Martin. 
George  H.  Ashley,  under  whose  supervision  the  work  was  done, 
visited  the  field  and  went  over  some  of  the  more  critical  points. 

GEOGRAPHY. 

Location. — The  Johnstown  quadrangle  is  situated  in  southwest- 
central  Pennsylvania,  mostly  in  Cambria  County,  but  extending  also 
over  small  parts  of  Somerset,  Westmoreland,  and  Indiana  counties. 
(See  PI.  I,  pocket.)  Its  area  is  about  228  square  miles.  It  lies  near 
the  eastern  edge  of  the  Allegheny  Plateau  province  and  near  the 
northeastern  edge  of  the  great  bituminous  coal  field  that  extends 
from  the  southern  part  of  New  York  to  northern  Alabama;  its  position 
in  this  fieldis  shown  in  Plate  II. 

Commercial  geography. — This  quadrangle  lies  in  the  plateau  region 
west  of  the  Allegheny  Front.  Its  most  important  streams  areCone- 
maugh  River  (formed  by  the  union  of  Stony  Creek  and  Little  Cone- 
maugh  River  at  Johnstown),  Blacklick  Creek  and  its  South  Branch, 
and  South  Fork  of  Conemaugh  River.  Conemaugh  River  has  long 
afforded  one  of  the  most  available  highways  of  communication  across 
the  region  from  the  coast  to  the  Middle  West;  the  first  railroad  (the 
old  Portage  and  Canal  route)  and  the  main  line  of  the  Pennsylvania 
Railroad  have  both  used  this  valley.  The  development  of  the  iron 


9 


10  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

resources  of  the  region  was  thus  early  stimulated,  and  in  turn  an 
impetus  was  given  to  the  development  of  the  coal  resources,  until  at 
the  present  time  Johnstown  and  the  neighboring  towns  are  among 
the  leading  coal  and  iron  centers  of  western  Pennsylvania. 

Stony  Creek  flows  northward,  in  its  course  forming  part  of  the 
boundary  between  Somerset  and  Cambria  counties,  this  part  of  its 
course  lying  entirely  within  the  Johnstown  Basin.  The  South  Fork 
of  Conemaugh  River  heads  near  the  summit  of  Allegheny  Mountain, 
near  the  Cambria-Bedford  county  line  in  the  Ebensburg  quadrangle, 
which  adjoins  the  Johnstown  quadrangle  on  the  east.  South  and 
North  branches  of  Blacklick  Creek  join  near  Vintondale  and  the  main 
stream  continues  westward  along  the  northern  edge  of  the  area.  In 
a general  way  the  drainage  of  the  quadrangle  flows  from  east  to 
west.  The  main  structural  and  to  a less  noticeable  extent  the  main 
topographic  features  trend  northeast  and  southwest.  The  drainage 
and  structure  thus  intersect  at  a fairly  large  angle — a condition  which 
has  proved  of  vast  economic  importance,  for  it  has  resulted  in  the 
cutting  of  deep  valleys  and  the  exposing  of  valuable  clay  and  coal 
beds.  Moreover,  it  has  made  possible  the  exploitation  on  a large 
scale  of  the  mineral  wealth  by  drifting  along  the  outcrop — a much 
safer  and  cheaper  method  than  shafting  and  one  tending  to  the  most 
rapid  development  of  a coal  region.  The  streams  have  determined 
the  location  of  the  local  railway  systems  and  have  made  their  con- 
struction fairly  easy. 

TOPOGRAPHY. 

RELIEF. 

The  form  of  the  surface  of  the  Johnstown  quadrangle  bears  a close 
and  striking  relation  to  the  geology  and  structure.  The  highest 
points  in  the  area  are  along  the  crest  of  Laurel  Ridge,  which  south 
of  Conemaugh  River  is  more  than  2,700  feet  high  at  a few  points. 
Laurel  Ridge  is  a structural  feature — that  is,  it  is  dependent  on  the 
character  of  the  rocks  brought  to  the  surface  by  the  structure.  These 
are  largely  the  sandstones  of  the  Pocono  and  Pottsville  formations. 
Where  rocks  of  this  character  cover  the  surface  the  country  is  wild 
and  surface  cultivation  is  out  of  the  question.  Farther  north  along 
the  ridge  the  sandy  sediments  dip  below  drainage  level  and  the  rocks 
of  the  Allegheny  formation  (“ Lower  Productive  Coal  Measures”)  and 
the  Conemaugh  formation  (“Lower  Barren  Coal  Measures”)  appear 
in  the  hills,  as,  for  instance,  along  South  Branch  of  Blacklick  Creek. 
The  changes  in  vegetation  and  general  conditions  accompanying  the 
gradual  disappearance  of  the  sandy  beds  below  the  surface  are  notice- 
able north  of  South  Branch  of  Blacklick  Creek,  and  in  this  region  the 
country  is  almost  all  under  cultivation. 

In  the  southeast  corner  of  the  quadrangle  the  highest  hills  are  a 
little  more  than  2,700  feet  high.  Here  also  the  beds  are  involved  in 


TOPOGRAPHY. 


11 


the  structural  uplift  along  the  front  of  Allegheny  Mountain,  and  the 
rocks  along  the  crest  of  the  mountain  are  chiefly  the  same  sand- 
stones as  occur  on  Laurel  Ridge. 

The  lowest  points  in  the  area  are  on  Conemaugh  River,  at  the  west- 
ern edge  of  the  quadrangle.  At  Conemaugh  Furnace  station  the 
elevation  is  1,134.54  feet.  The  extremes  in  the  topography  are  well 
brought  out  near  by,  for  Conemaugh  River  in  descending  from  1,185 
feet  at  Johnstown  to  1,135  feet  at  Conemaugh  Furnace  flows  through 
a gorge  the  hills  on  either  side  of  which  rise  1,600  feet  higher. 

The  greater  portion  of  the  area  has  an  elevation  between  the 
extremes  given  above.  In  detail  the  surface  is  decidedly  hilly,  but 
most  of  the  hill  slopes  are  rather  gentle,  especially  back  from  the 
main  drainage  channels.  The  badly  dissected  character  of  the  ridge 
has,  however,  an  important  bearing  on  the  availability  and  exploita- 
tion of  the  natural  resources  of  the  region.  There  is  very  little  level 
land  in  the  quadrangle,  what  there  is  being  confined  almost  solely  to 
the  lower  stretches  of  Blacklick  Creek  in  Indiana  County. 

Points  of  equal  elevation  are  represented  on  the  contour  map  by 
light-brown  lines,  which  really  represent  the  intersections  of  hypo- 
thetical horizontal  planes  with  the  surface  of  the  country.  They  are 
placed  20  feet  apart  and  indicate  the  “lay  of  the  land”  with  great 
precision. 

SURVEYS. 

TRI ANGULATION  STATIONS. 

The  topographic  work  for  the  map  of  the  Johnstown  quadrangle 
(PI.  I)  is  based  on  triangulation 
stations  established  by  the  United 
States  Geological  Survey  within  the 
boundaries  of  the  quadrangle  or 
comparatively  near  its  borders  to 
the  east  and  north.  (See  fig.  1.) 

Descriptions  of  the  exact  locations 
of  these  triangulation  stations  are 
given  below: 

CHICKAREE,  CAMBRIA  COUNTY. 

On  a cleared  knob  in  the  central 
part  of  Jackson  Township,  10  miles 
by  road  westward  from  Ebensburg, 

300  yards  south  of  the  Chickaree 
Hill  schoolhouse. 

Station  mark:  A marble  post  34  by  6 by  6 inches  set  32  inches  in 
the  ground,  in  the  center  of  top  of  which  is  countersunk  and  cemented 
a bronze  triangulation  tablet. 


Figure  1. — Sketch  map  showing  location  of  tri- 
angulation stations  on  which  survey  of  Johns- 
town quadrangle  is  based. 


12  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


[Latitude  40°  26'  38.97".  Longitude  78°  52'  48.29".] 


To  station — 

Azimuth. 

Back  azimuth. 

Log.  dis- 
tance. 

Ebensburg 

251  24  48.82 
292  00  35.81 
318  31  18.78 

71  30  51.47 
112  04  41.22 
138  37  47.50 

Meters. 

4. 1425539 

3.  9833693 

4.  3303852 

Wess 

Fye 

EBENSBURG,  CAMBRIA  COUNTY. 

Station  is  center  of  cupola  of  courthouse  in  Ebensburg. 
Station  mark:  Center  of  cupola. 


[Latitude  40°  29'  02.07".  Longitude  78°  43'  29.50".] 


To  station— 

Azimuth. 

Back 

azimuth. 

Log.  dis- 
tance. 

o 

tt 

o 

/ 

// 

Meters. 

Thomas 

156 

58 

25.25 

336 

57 

06. 21 

3. 8644894 

Carrolltown 

185 

49 

38.  40 

5 

50 

15.62 

4. 1222362 

Wopsononock 

248 

52 

46.  94 

69 

03 

52. 34 

4.  4120176 

Tunnel  Hill 

270 

56 

22.  25 

91 

03 

22.  64 

4. 1833793 

Sherbine 

0 

52 

21.75 

180 

52 

15.82 

4. 1515885 

Wess 

27 

55 

04. 38 

207 

53 

07. 38 

3.  9581867 

Chickaree 

71 

30 

51.47 

251 

24 

48.82 

4. 1425539 

WESS,  CAMBRIA  COUNTY. 

In  the  northern  portion  of  Croyle  Township,  8 miles  southwest  of 
Ebensburg,  1 mile  west  of  New  Germany,  in  a pasture  owned  by  Leo 
Wess.  Theodolite  elevated  35  feet. 

Station  mark:  A marble  post  36  by  6 by  6 inches  set  32  inches  in 
the  ground,  in  the  center  of  the  top  of  which  is  countersunk  and 
cemented  a bronze  triangulation  tablet. 

Reference  mark:  Line  fence  due  north  44  feet  distant.  Center  of 
big  dead  tree,  N.  65°  W.  (magnetic),  31  feet  distant. 

[Latitude  40°  24'  41.86".  Longitude  78°  46'  29.85".] 


To  station— 

Azimuth. 

Back  azimuth. 

Log.  dis- 
tance. 

Chickaree 

112  04  41.22 
185  20  37.23 
207  53  07.38 
326  41  29.11 
337  09  43.27 

Of  If 

292  00  35.81 
5 21  15. 32 
27  55  04.38 
146  43  20.03 
157  12  06.81 

Meters. 

3.  9833693 
4. 1710473 
3.  95&1867 
3.  8666773 
4. 1299536 

Thomas 

Ebensburg 

Sherbine 

Fye 

SHERBINE,  CAMBRIA  COUNTY. 

On  a small  hill  having  scattering  locust  trees  on  its  summit,  in 
Croyle  Township,  about  one-fourth  mile  west  of  the  Summerhill 
Township  line,  2 miles  southwest  of  Wilmore,  2 miles  southeast  of 
Summerhill  post-office,  on  land  of  Aaron  Sherbine.  Theodolite 
elevated  28  feet. 


TOPOGRAPHY. 


13 


Station  mark:  A marble  post  36  by  6 by  6 inches  set  32  inches  in 
the  ground,  in  the  center  of  top  of  which  is  countersunk  and  cemented 
a bronze  triangulation  tablet. 


[Latitude  40°  21'  22.50".  Longitude  78°  43'  38.65".] 


To  station— 

Azimuth. 

Back  azimuth. 

Log.  dis- 
tance. 

Wess 

146  43  20.03 
180  52  15.82 
228  00  07.85 
349  15  37.33 

326  41  29.11 
0 52  21.75 
48  07  13.50 
169  16  09.98 

Meters. 

3.  8666773 
4. 1515885 

4.  3183273 
3. 8058254 

Ebensburg 

Tunnel  Hill 

Fye 

FYE,  CAMBRIA  COUNTY. 

[Not  occupied.] 

A cleared  ridge  known  as  the  Fye  place,  owned  by  the  Mountain 
Coal  Company,  in  Adams  Township,  6 miles  south  of  Summerhill  and 
7 miles  southeast  of  South  Fork. 

Station  mark:  A marble  post  36  by  6 by  6 inches  set  32  inches  in 
the  ground,  in  the  center  of  top  of  which  is  countersunk  and  cemented 
a bronze  triangulation  tablet. 

Reference  mark:  The  lone  locust  signal  tree  4 feet  north  of  station 
mark. 


[Latitude  40°  17'  58.79".  Longitude  78°  42'  48.19".] 


To  station— 

Azimuth. 

Back  azimuth. 

Log.  dis- 
tance. 

Chickaree 

Wess 

138  37  47.50 
157  12  06.81 
169  16  09.98 

318  31  18.78 
337  09  43.27 
349  15  37.33 

Meters. 

4. 3303852 
4. 1299536 
3. 8058254 

Sherbine 

SPIRIT  LEVELING. 


The  topography  of  the  Johnstown  quadrangle  is  shown  on  Plate  I 
by  buff-colored  contour  lines  based  on  precise  levels  run  by  the  United 
States  Geological  Survey.  In  running  these  levels  numerous  bench 
marks  were  established,  their  elevations  being  based  on  an  aluminum 
tablet  in  the  foundation  of  the  Seventh  Avenue  Hotel,  Pittsburg,  Pa., 
marked  “ 738  Pittsburg,  1899,”  the  elevation  of  which  is  now  accepted 
as  738.384  feet  above  mean  sea  level.  The  initial  points  on  which 
these  levels  depend  are  various  bench  marks  along  the  precise-level 
lines  of  the  Pennsylvania  Railroad,  the  accepted  heights  having  been 
determined  by  the  1903  adjustment. 

The  work  on  the  Johnstown  quadrangle  was  done  by  Mr.  George 
Seidel,  levelman,  in  1902. 


14  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


The  descriptions  and  elevations  of  these  bench  marks  are  given 
below: 

Johnstown  south  along  Baltimore  and  Ohio  Railroad  to  Ingleside. 

Feet. 

Johnstown,  at  west  end  of  north  parapet  of  railroad  bridge;  copper  bolt 

(Pennsylvania  Railroad  bench  mark) ],  180.  27 

Johnstown,  east  end  of  south  parapet  of  Pennsylvania  Railroad  bridge; 

aluminum  tablet  stamped  “1180  PITTS  ” 1, 180.  261 

Johnstown,  railroad  ticket  office,  on  window  sill;  chiseled  shelf  (Pennsyl- 
vania Railroad  bench  mark) l}  187.  60 

Johnstown,  road  crossing  at  Pennsylvania  Railroad  station;  top  of  rail 1, 184 

Johnstown,  in  front  of  Baltimore  and  Ohio  Railroad  station;  top  of  rail 1, 169 

Stony  Creek,  road  crossing  at  station;  top  of  rail 1, 194 

Johnstown,  3 miles  south  of,  Baltimore  and  Ohio  Railroad  and  trolley  grade 

crossing;  top  of  rail 1, 191 

Kring,  road  crossing  at  station;  top  of  rail 1,  241 

Ingleside,  700  feet  north  of,  northeast  corner  of  small  railroad  bridge;  cop- 
per bolt  marked  “1275  PITTS  ” 1,  275.  610 

Ingleside  northeast  along  Pennsylvania  Railroad  via  Elkton  to  Salix. 

Scalp  Level,  0.45  mile  north  of,  west  side  of  track,  75  feet  west  of  tool  house. 

in  large  sandstone;  aluminum  tablet  stamped  “1719  PITTS  ” 1,  719.  225 

Salix,  870  feet  north  of  station,  under  Pennsylvania  Railroad  culvert,  west 

wall;  bronze  tablet  stamped  “2050  PITTS” 2,  049.  455 

Salix,  railroad  bridge  at  station,  north  parapet,  east  end;  aluminum  tablet 
stamped  “2077  PITTS” 2,077.762 

Seward  northeast  along  Pennsylvania  Railroad  via  Vintondale  and  Nanty  Glo  to 

Ebensburg. 

Seward,  0.17  mile  west  of  V.  K.  tower,  railroad  bridge  No.  226  over  Piney 
Run,  north  parapet,  east  end  of  arch;  copper  bolt  (Pennsylvania  Railroad 

bench  mark) 1,  091.  571 

Seward,  doorstep  of  waiting  room  of  station;  copper  bolt  marked  “1122 

U.  S.” 1,122.145 

Seward,  crossing  at  station;  top  of  rail 1, 120 

Wehrum,  crossing  at  station;  top  of  rail 1,  360 

Vintondale,  150  feet  east  of  station,  iron  bridge,  south  end  of  west  abutment; 

aluminum  tablet  stamped  “1403  PITTS  ” 1,  402.  741 

Twin  Rocks,  crossing  at  station;  top  of  high  rail 1,  668 

Nanty  Glo,  200  feet  south  of  station,  iron  bridge,  west  end  of  north  abutment; 

bronze  tablet  stamped  “1706  PITTS  ” 1,  705.  761 

Nanty  Glo,  crossing  at  station;  top  of  high  rail 1,  710 

Beulah  Road,  in  front  of  station;  top  of  rail 1,  894 

STRATIGRAPHY. 

GENERAL  STATEMENT. 

The  surface  rocks  in  the  Johnstown  quadrangle  are  entirely  of 
sedimentary  origin,  all  of  them  having  been  deposited  in  or  by  water. 
They  consist  of  sandstones,  shales,  limestones,  and  coal  and  iron-ore 
beds,  the  whole  having  a thickness  of  approximately  3,100  to  3,200 


STRATIGRAPHY. 


15 


feet.  These  rocks  belong  in  the  Devonian  and  Carboniferous 
systems,  except  for  the  imperfectly  consolidated  gravels  of  the  river 
terraces,  which  are  tentatively  regarded  as  of  Pleistocene  age,  and 
the  recent  alluvium  of  the  flood  plains.  The  Carboniferous  rocks 
are  of  chief  importance,  as  they  contain  the  workable  coals  and  clays. 
All  these  rocks  will  be  described  in  descending  order,  beginning 
with  the  youngest. 

QUATERNARY  SYSTEM. 

RECENT  RIVER  DEPOSITS  (ALLUVIUM). 

The  alluvium  of  the  streams  of  this  area  is  the  youngest  bedded 
deposit.  It  consists  of  fine  material,  chiefly  sand  and  clay,  laid  down 
by  the  present  streams  during  periods  of  high  water,  and  is  present  in 
varying  amounts  along  most  of  the  streams,  though  occupying  as  a 
rule  small  areas  only.  The  most  important  alluvial  area  is  that  at  the 
confluence  of  Conemaugh  River  and  Stony  Creek,  on  which  the  greater 
part  of  the  city  of  Johnstown  and  its  suburbs  is  located.  Other 
important  areas  of  alluvium  are  found  on  Blacklick  Creek  near  the 
northwestern  corner  of  the  quadrangle.  All  the  level  land  in  this 
part  of  the  quadrangle  is  under  cultivation. 

PLEISTOCENE  DEPOSITS. 

Along  Conemaugh  River  and  Stony  Creek  occur  deposits  which 
can  not  be  correlated  strictly  with  the  alluvium  or  recent  flood-plain 
deposits.  This  material,  which  consists  of  rounded  bowlders  varying 
up  to  2 or  3 feet  in  greatest  dimension,  mingled  with  sand  and  clay  in 
small  quantities,  is  found  at  two  or  more  distinct  horizons.  The  lower 
deposit  is  well  developed  along  the  main  line  of  the  Pennsylvania 
Railroad  and  is  shown  in  small  cuts  a short  distance  east  of  Mineral 
Point.  On  the  Baltimore  and  Ohio  Railroad  a short  distance  south 
of  the  quadrangle,  north  of  the  mouth  of  Paint  Creek,  near  Kring, 
and  near  the  suburb  of  Roxbury  are  also  excellent  exposures.  At 
the  quarry  of  B.  H.  Campbell,  north  of  Sheridan,  rounded  bowlders 
occur  100  feet  above  the  level  of  the  Pennsylvania  Railroad.  This 
deposit  is  similar  in  all  respects  to  the  lower  one  occurring  along 
Stony  Creek.  These  bowlders  show  in  the  foreground  of  Plate  V,  B 
(p.  28).  The  material  is  considered  to  be  Pleistocene  in  age.  It  has 
no  economic  importance. 


16  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

CARBONIFEROUS  SYSTEM. 

PENNSYLVANIAN  SERIES. 

CONEMAUGH  FORMATION. 

GENERAL  CHARACTER. 

The  Conemaugh  formation  includes  the  rocks  lying  below  the  Pitts- 
burg coal  and  above  the  Upper  Freeport  coal.  A nearly  complete 
section  of  these  rocks  was  obtained  from  drill  records  and  by  hand- 
level  work  along  the  Pennsylvania  Railroad  in  the  deepest  part  of  the 
Wilmore  structural  basin.  The  upper  200  feet  or  so  of  the  section 
represents  barometric  work  along  the  roads  in  the  Ebensburg  quad- 
rangle to  the  east.  It  has  been  thought  advisable  to  give  the  section 
of  the  Conemaugh  thus  obtained  in  this  locality  as  a matter  of  record, 
but  it  will  be  understood  that  such  a detailed  section  necessarily  is 
constant  over  a very  small  area.  Some  of  the  sandstones,  for  instance, 
die  out  completely  within  a short  distance  and  other  lentils  appear 
in  the  section  either  slightly  higher  up  or  lower  down.  In  general, 
local  names  are  applied  to  such  sandstone  lentils  where  their  position 
is  known  to  be  fairly  well  defined  in  the  geologic  column. 

The  section  of  the  Conemaugh  formation  is  as  follows : 

Section  of  the  Conemaugh  formation  in  the  Wilmore  Basin. a 


Sandstones  and  sandy  shale  layers  with  intercalated  limestones 

Shale 

Sandstone  (Wilmore) 

Shale 

Limestone,  sandy 

Shale,  green,  weathering  to  clay 

Shale,  dark  drab 

Sandstone,  containing  a 10  to  12  inch  limestone  layer  and  with  a possible  coal  bloom. . 

Shale 

Limestone 

Shale,  green 

Limestone 

Shale,  concretionary 

Fireclay 

Shale,  concretionary 

Shale,  olive 

Shale,  dark 

Sandstone 

Shale,  blue-black 

Limestone 

Shale 

Sandstone  (Summerhill) 

Shale,  with  sandy  and  limestone  layers 

Sandstone,  shaly 

Shale,  dark  blue,  weathering  like  sandstone 

Sandstone 

Limestone 

Limestone  grading  into  sandstone 

Sandstone,  hard,  grav. .) 

Shale [Morgantown  (“  Ebensburg”)  sandstone  member 

Sandstone,  hard,  gray . . J 

Shale,  sandy 

Sandstone 


Thick- 

ness. 

Total. 

Ft.  in. 

Ft.  in. 

200« 

200 

20 

220 

17 

237 

5 

242 

2 

244 

23 

267 

15 

282 

6 

288 

10 

298 

9 

307 

6 

313 

1 

314 

2 

316 

1 

317 

4 

321 

1 

322 

10 

332 

1 

333 

3 

336 

3 

339 

20 

359 

45 

404 

30 

434' 

25 

459 

25 

484 

2 

486 

3 

489 

6 

495 

1 25 

520 

520  3J 

1 7 5J 

527  9 

3 2 

530  11 

5 1 

536 

a First  200  feet,  barometric  measurements  along  roads;  section  hand-leveled  from  200  to  495  feet;  below 
495  feet  record  obtained  from  a bore  hole  on  the  Pennsylvania  Railroad  opposite  the  signal  tower  between 
Wilmore  and  Summerhill. 


CARBONIFEROUS  SYSTEM. 


17 


Section  of  the  Conemaugh  formation  in  the  Wilmore  Basin — Continued. 


Thick- 

ness. 

Total. 

Ft.  in. 

Ft.  in. 

9 24 

10 

545  24 

Coal  (called  600-foot  rider  owing  to  its  position  at  about  600  feet  above  the  Lower 
Kittanning  or  B coal) 

546  4 

Shale 

29  2 

575  2J 
581  34 

588  101 
607  2\ 

613  10| 

6 1 

Shale' 

7 7 

Sandstone  and  shale 

18  4 

Shale,  calcareous 

6 8 

Shale'with  calcareous  and  clay  streaks 

13  2 

627  \ 

Shale,  sandy 

8 10 

635  104 

Shale 

3 5 

639  3| 

6 104 

7 10“ 

646  2 

Shale,  sandy 

654 

Sandstone 

31  2\ 

8 

685  24 

Shale,  with  bony  streaks 

685  104 
701  4 

Sandstone 

15  5J 
4 10i 

f 19 

Shale 

706.  24 

Shale,  sandy. ] 

725  24 

Sandstone >Buffalo  sandstone  member 

J 28  1 

753  34 

Slate  and  sandstone. . J 

l 12  3 

765  6| 

Sandstone  with  congomerlate  layers 

55  24 

820  9 

Slate 

4 3 

825 

Slate,  sandy 

7 6 

832  6 

Slate 

28  64 
7 6|- 

m 

861  4 

Slate,  sandy 

868  7 

Shale 

869  64 

874  4 

Slate,  sandy 

4 6" 

Slate 

11  7J 

885  8 

Sandstone 

3 4 

889 

Shale 

10  3 

899  3 

Shale,  red 

4 11 

904  2 

Sandstone 

10  3 

914  5 

Shale 

8 3 

922  8 

Sandstone 

2 81 
21  6 

925  44 

Shale  with  sandstone  layers 

946  104 

947  10 

Sandstone 

HI 

1 3 

Slate 

949  1 

Sandstone 

10  1 

959  2 

Slate 

5 

964  2 

Top  of  Upper  Freeport  coal. 

With  this  section  may  be  compared  the  following  section  of  a part 
of  the  Conemaugh,  measured  by  John  Fulton,  in  Prossers  Knob,  near 
Johnstown:® 

Section  of  part  of  the  Conemaugh  formation  in  Prossers  Knob,  near  Johnstown. 


Ft.  in. 

Stone  quarry ; sandstone 20 

Shales,  olive 17 

Shales,  drab 18 

Sandstone,  thin  bedded 10 

Shales 8 

Iron  ore,  siliceous 3 

Shales,  olive  and  drab 68 

Shales,  red 10 

Shales,  olive 12 

Slate  and  sandstone 10 

Sandstone-,  white 26 

Shales,  drab 13 

Sandstone,  massive,  drab,  forming  cliff 20 

Coal 3 


a Second  Geol.  Survey  Pennsylvania,  Rept.  H2,  p.  97. 
69516°— Bull.  447—11 2 


18  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Shale,  drab 

Sandstone,  drab 

Slates 

Johnstown  iron-ore  seam 

Shales,  flesh  and  drab  colored. 

Shales,  iron  stained 

Iron  ore 

Fire  clay 

Shales,  soft,  drab 

Fire  clay  and  shales 

Shales,  drab,  and  sandstone  ... 

Coal,  Upper  Freeport  or  E 


Place  of  the  Mahoning  sand- 
stone. 


Ft. 

4 

7 
2 
2 

13 

9 

2 

8 
4 

15 

3 


in. 


10 


According  to  the  section  (pp.  16-17),  the  Conemaugh  is  nearly  1,000 
feet  thick,  this  estimate,  however,  being  subject  to  the  question  of  the 
correct  correlation  of  the  Pittsburg  coal.  It  is  made  up  essentially 
of  shales  and  sandstones,  with  a few  beds  of  limestone.  Streaks  of 
coal  are  present  here  and  there,  hut  only  locally  are  they  of  sufficient 
thickness  and  purity  to  be  worked  even  in  a small  way.  Fire  clay, 
both  plastic  and  flint,  occurs  in  the  formation  in  certain  parts  of  the 
area.  A bed  of  iron  ore  described  in  the  reports  of  the  Second  Geo- 
logical Survey  of  Pennsylvania  as  the  Johnstown  ore  has  been  found 
on  Mill  Creek,  north  and  west  of  Johnstown,  and  near  the  position  of 
the  old  Cambria  furnace  at  the  base  of  Laurel  Hill;  it  lies  50  feet 
above  the  Upper  Freeport  coal.  Considerable  historical  importance 
attaches  to  this  ore  body,  for  its  presence  determined  the  beginning 
of  the  iron  industry  near  Johnstown  and  undoubtedly  influenced  the 
present  vigorous  development  of  the  coal. 


DETAILED  DESCRIPTION. 

The  higher  portion  of  the  Conemaugh  in  the  Johnstown  quadrangle 
is  made  up  of  sandstones  and  shales,  with  occasional  beds  of  limestone. 
As  it  has  been  found  difficult  to  correlate  these  sandstones  with  the 
typical  members  in  the  Pittsburg  district  and  Allegheny  Valley,  they 
.are  here  referred  to  by  the  local  names  given  them  in  the  Ebensburg 
quadrangle,  which  lies  immediately  east  of  the  area  under  discussion. 

Wilmore  sandstone  member. — The  highest  of  these  sandstones  was 
called  by  Butts  a the  Wilmore  sandstone.  It  shows  in  the  top  of  the 
first  railway  cut  west  of  Wilmore  and  in  the  neighboring  hills.  Its 
position  with  reference  to  the  Upper  Freeport  coal  is  indicated  in  the 
section  on  pages  16-17.  It  is  usually  not  more  than  20  feet  thick. 

Summerhill  sandstone  member. — Next  comes  the  Summerhill  sand- 
stone member,  whose  base  lies  560  feet  above  the  Upper  Freeport 
coal.  It  varies  from  30  to  45  feet  in  thickness.  It  was  named  by 


Ebensburg  folio  (No.  133),  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1905,  p.  5. 


CARBONIFEROUS  SYSTEM. 


19 


Butts  from  the  village  of  Summerhill,  in  the  eastern  part  of  the 
Johnstown  quadrangle.  It  outcrops  conspicuously  in  all  the  hills 
between  Wilmore  and  Summerhill,  especially  in  a bluff  east  of  the 
latter  town.  It  is  as  a rule  decidedly  laminated  in  appearance,  differ- 
ing in  this  respect  from  the  massive  Morgantown  (‘  ‘Ebensburg”)  sand- 
stone below. 

Morgantown  ((C  Ebensburg”)  sandstone  member. — The  next  lower 
stratum  of  note  in  this  area  is  a sandstone  which  Butts  called  the 
Ebensburg,  but  which  in  this  report  will  be  termed  the  Morgantown 
sandstone  member.  This  sandstone  lies  between  400  and  450  feet 
above  the  Upper  Freeport  coal  in  the  southeastern  part  of  the  quad- 
rangle and  probably  less  than  400  feet  above  it  in  the  northern  part. 
It  is  excellently  developed  near  Elton  in  the  Johnstown  area. 

Harlem  ( ?)  coal. — The  Morgantown  sandstone  is  closely  underlain 
by  a thin  coal  known  as  the  600-foot  rider,  as  it  is  usually  600  feet 
above  the  Lower  Kittanning  coal.  It  outcrops  near  the  old  dam 
site  on  South  Fork  of  Conemaugh  River  (PL  III,  A).  It  is  possible 
that  this  corresponds  to  the  Harlem  or  Friendsville  coal,  but  this 
correlation  is  provisional,  as  it  is  hazardous  to  attempt  close  corre- 
lation with  the  upper  portions  of  the  Conemaugh  in  the  western  part 
of  the  State. 

Red  shale. — The  next  lower  stratum  persistent  enough  to  be  traced 
with  certainty  is  a band  of  red  shales  30  feet  or  less  in  thickness. 
These  occur  in  nearly  all  parts  of  the  quadrangle,  though  the  distance 
of  their  top  above  the  Upper  Freeport  coal  is  not  constant,  varying 
from  300  to  400  feet.  They  may  correspond  to  the  red  shale  in  the 
western  part  of  the  State,  to  which  I.  C.  White  has  given  the  name 
Pittsburg  red  shales. 

Saltsburg  sandstone  member. — Around  Johnstown  the  top  of  what 
is  regarded  as  the  representative  of  the  Saltsburg  sandstone  member 
lies  about  300  feet  above  the  Upper  Freeport  coal.  It  is  very  nearly 
50  feet  thick  and  is  fairly  massive  in  the  hills  east  of  the  town.  It  is 
underlain  in  this  region  by  a thin  band  of  reddish  and  purple  shales. 

In  the  southeastern  part  of  the  quadrangle  the  Saltsburg  horizon 
is  for  the  most  part  below  drainage  level,  but  several  apparently 
carefully  kept  drill  records  give  an  excellent  idea  of  its  character. 
Its  top  is  here  300  feet' above  the,  Upper  Freeport  coal,  and  it  is  about 
50  feet  thick.  It  is  underlain  by  30  to  40  feet  of  shales  containing  a 
coal  (the  Bakerstown  bed)  or,  in  one  section,  two  coals  separated  by 
25  feet  of  shales  and  sandy  shales.  Red  shale  also  appears  in  this 
shale  interval,  and  not  more  than  25  feet  above  this  a slightly  cal- 
careous bed,  very  thin,  may  possibly  represent  the  Upper  Cambridge 
limestone.  Both  near  Johnstown  and  in  the  southeastern  part  of 
the  quadrangle  these  sandstones  in  places  become  sandy  shales  and 


20  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

merge  imperceptibly  with  the  beds  above  or  below,  so  that  it  is  diffi- 
cult or  impossible  to  locate  their  bases  and  tops  in  the  records. 

Buffalo  sandstone  member. — In  the  South  Fork  district  the  top  of 
the  Buffalo  sandstone  member  is  about  200  feet  above  the  Upper 
Freeport  coal.  As  nearly  as  can  be  ascertained  from  the  road  sec- 
tions, the  sandstone  consists  of  a single  member.  It  appears  promi- 
nently along  the  Pennsylvania  Railroad  near  Ehrenfeld,  where  the 
debris  from  it  is  massive,  and  is  well  exposed  in  the  shallow  railroad 
cuts  west  of  Summerhill  station.  Compactly  bedded  thick  and  thin 
flags  are  very  characteristic  of  this  stratum  in  the  eastern  part  of  the 
Johnstown  quadrangle  and  farther  east  in  the  Ebensburg  quadrangle. 

Along  Blacklick  Creek  in  the  northwestern  part  of  the  quadrangle 
there  appears  in  the  section  a very  massive  sandstone,  whose  top  is 
200  to  235  feet  above  the  Lower  Freeport  coal  and  80  and  95  feet, 
respectively,  above  the  Mahoning  coal  and  Johnstown  ore  bed.  This 
sandstone  probably  corresponds  to  the  Buffalo  sandstone  member. 
It  is  exceedingly  massive,  forming  debris  comparable  to  that  from 
the  Pottsville.  It  makes  a very  prominent  appearance  north  of 
Vintondale  and  to  the  west  in  Indiana  County. 

Gallitzin  coal. — The  Gallitzin  coal  ranges  from  70  to  125  feet  above 
the  top  of  the  Upper  Freeport  coal  in  the  region  around  Johnstown. 
In  some  of  the  diamond-drill  records  from  the  hills  east  of  the  city 
it  appears  about  110  feet  above  the  top  of  the  Upper  Freeport  coal. 
In  some  of  the  sections  a coal  appears  as  near  the  Upper  Freeport 
as  70  feet.  Where  there  is  but  a single  coal  in  the  lower  125  feet  of 
the  Conemaugh  and  it  is  as  near  to  the  Upper  Freeport  as  70  feet 
there  is  always  doubt  as  to  whether  it  should  be  regarded  as  the  Gal- 
litzin or  as  a lower  coal.  The  Gallitzin  coal  is  not  a commercial 
bed  and  has  not  been  worked  except  for  local  use  in  any  part  of  the 
quadrangle. 

Lower  red  shales. — The  Gallitzin  coal  is  underlain  by  a thin  band 
of  red  or  variegated  shales,  which  are  well  exposed  along  the  road 
ascending  to  Pleasant  Hill  in  the  western  part  of  Johnstown.  In 
some  records  of  the  drill  holes  put  down  to  the  east  of  the  city  these 
shales  have  been  called  variegated. 

Mahoning  sandstone  member. — The  Mahoning  member  is  composed 
of  sandstones,  shales,  and  coals  tying  at  the  base  of  the  Conemaugh 
formation  between  the  Gallitzin  coal  and  the  Upper  Freeport  coal 
(top  of  the  Allegheny  formation).  It  is  Well  exposed  in  the  hills 
about  Johnstown  and  to  the  south  along  Stony  Creek,  near  South 
Fork,  and  near  Blacklick  Creek. 

At  the  tunnel  of  the  Baltimore  and  Ohio  Railroad  south  of  Johns- 
town the  following  clear-cut  section  of  the  lower  part  of  this  member 
was  obtained : 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  447  PLATE  III 


A.  SOUTH  FORK  AND  WASHED  AWAY  DAM. 

The  breaking  of  this  dam  caused  the  Johnstown  flood  of  May  31,1 889. 


B.  SANDSTONE  NEAR  BASE  OF  CONEMAUGH  FORMATION  NEAR  JOHNSTOWN. 


CARBONIFEROUS  SYSTEM. 


21 


Section  of  part  of  Mahoning  sandstone  member  south  of  Johnstown , Pa. 


Ft.  in. 

Sandstone,  laminated  and  cross-bedded,  upper  Mahoning 8 

Shale,  green 4 -5 

Coal 5 

Shale,  drab,  fossiliferous 2 

Coal 6 

Fire  clay,  dark,  almost  black 6 

Limestone,  blue,  ferruginous,  altering  to  ore  (“  Johnstown  ore”)  1^-2 

Shale 30 

Sandstone,  massive 20 

Shale,  massive,  brown 5 


This  section  may  be  considered  fairly  typical  for  this  immediate 
region.  The  upper  sandstone,  called  upper  Mahoning,  is  decidedly 
characteristic  in  appearance.  It  is  fine  grained,  weathering  into 
extremely  thin  slabs,  and  where  seen  to  greatest  advantage  ranges 
in  thickness  up  to  20  feet.  The  coal  below  it,  exposed  in  the  saddle 
in  the  road  above  the  tunnel,  is  present  in  two  benches  with  an  inter- 
val of  2 feet  between.  This  is  probably  the  Mahoning  coal.  It  is 
nowhere  of  workable  thickness  in  this  quadrangle. 

The  “Johnstown  ore”  underlies  the  Mahoning  coal  and  is  about 
50  feet  above  the  Upper  Freeport  coal.  As  a workable  ore  it  has 
been  found  only  in  the  center  of  the  Johnstown  Basin.  It  has  been 
worked  in  the  hills  about  the  city,  on  Hinckston  Run,  at  the  west 
base  of  Laurel  Ridge,  and  on  Mill  Creek.  At  present  it  is  of  no 
importance. 

Flint  clay  occurs  in  the  shale  interval  lying  above  the  lower  Mahon- 
ing 'sandstone.  It  lies  close  to  the  top  of  the  lower  sandstone  bed 
at  an  interval  ranging  from  50  to  80  feet  above  the  Upper  Freeport 
coal.  The  position  of  this  flint  clay  is  shown  in  the  section  in  the 
hill  east  of  Johnstown  (p.  116).  Its  characteristics  are  described 
later  (pp.  115-117). 

The  lower  Mahoning  sandstone  outcrops  in  all  the  hills  about 
Johnstown  and  has  been  quarried  for  building  stone  at  many  places. 
It  is  very  massive,  decidedly  coarse  grained,  and  micaceous.  As  a 
rule  it  ranges  from  20  to  30  feet  in  thickness  and  is  separated  from  the 
top  of  the  Upper  Freeport  coal  by  5 to  10  feet  of  dark-brown  shale. 

Near  South  Fork  the  base  of  the  Conemaugh  is  well  shown  in  a 
recent  cut  on  the  Pennsylvania  Railroad  near  Ehrenfeld.  A hand- 
leveled  section  obtained  opposite  the  station  is  as  follows: 

Section  of  the  base  of  Conemaugh  formation  at  Ehrenfeld. 

Ft.  in. 


Shale,  weathering  to  clay 15 

Shale,  olive  and  drab,  locally  sandy 30 

Coal 4-5 

Shale 8 

Shale,  black 2 


22  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Ft. 

Shales,  blue  and  black 1 

Coal , 2 

Shales 15 

Shale,  blue,  with  alternating  layers  of  fine-grained  sandstone 20 

Sandstone,  massive 20 

Upper  Freeport  coal. 


The  Mahoning  coal  appears  in  this  section,  as  in  that  south  of 
Johnstown,  in  two  benches  at  approximately  the  same  distance  above 
the  top  of  the  Upper  Freeport  coal.  The  lower  bench  is  thick 
enough  to  be  worked,  though  so  far  as  known  no  coal  has  ever  been 
obtained  from  it.  The  lower  Mahoning  sandstone  is  fairly  massive, 
but  hot  so  much  so  as  in  the  hills  near  Johnstown. 

In  the  hills  bordering  Blacklick  Creek,  near  Wehrum,  the  Mahoning 
coal  measures  about  a foot  in  thickness  and  is  closely  underlain  by 
old  ore  benches,  indicating  the  formerly  extensive  workings  on  the 
Johnstown  iron-ore  bed.  The  underlying  flint  clay  is  present  north, 
west,  and  southwest  of  Wehrum  in  a position  similar  with  respect  to 
the  lower  Mahoning  sandstone  to  that  of  the  flint  clay  occurring 
above  the  same  sandstone  near  Johnstown,  and  is  thus  to  be  corre- 
lated with  that  stratum.  The  lower  Mahoning  sandstone  is  per- 
sistent where  it  appears  above  drainage  level  in  the  Blacklick  Creek 
district,  and  is  fairly  massive. 

ALLEGHENY  FORMATION. 


GENERAL  CHARACTER. 

The  Allegheny  formation  was  originally  known  as  the  “Lower 
Productive  Coal  Measures. ” As  may  be  inferred  from  that  name, 
it  is  distinguished  from  the  overlying  formation  by  the  presence  of 
several  workable  coal  beds.  It  is  the  most  important  formation  in 
the  Johnstown  quadrangle,  as  in  it  are  found  all  the  workable  coals 
of  the  area.  The  following  section,  compiled  from  the  area  about 
Johnstown  and  to  the  south,  gives  an  idea  of  the  general  character 
of  the  formation  in  this  quadrangle: 


Section  of  Allegheny  formation  about  Johnstown  and  to  the  south. 

Ft. 

Coal,  Upper  Freeport  (Coke  Yard  or  E coal) 3 

Shale 14 

Shale  with  limestone  concretions 

Shales,  bluish 


Sandstone,  laminated . . . 
Shales  and  sandy  shales  . 

Coal,  1 foot 

Bone,  U inches 

Coal,  1 foot  7 inches. 

Bone,  1 inch 

Coal,  3J  inches 


Lower  Freeport  (D  or  Limestone 
coal). 


in. 

3 


3 1 


CARBONIFEROUS  SYSTEM. 


23 


Ft. 

Limestone 3| 

Shale,  blue 5 

Shale,  light  drab,  ferruginous 7 

Shale,  sandy 

Shale,  blue  black 4 

Coal,  Upper  Kittanning  (C/  or  Cement  coal) 3f 

Shale 1 

Limestone 5 

Shale 3$ 

Shale,  sandy 

Shale,  black  and  brown 

Coal 

Shales,  sandy 

Shales 

Coal 

Shale 

Interval,  chiefly  sandstone 20-25 

Coal,  3 feet  8J  inches 

Bone  or  black  shale,  3|  inches. . 

Coal,  3J  inches 

Bone,  1 inch 

Coal,  10  inches 

Fire  clay 

Sandstone,  gray,  laminated 9 

Sandstone,  massive 40 

Shale 2 

Coal  and  bone  (Clarion  or  A/ coal) 3 

Shale 10 

Sandstone,  blue,  laminated 5 

Pottsville.  

280 
to  285 


Lower  Kittanning  (Mil- 
ler or  B coal). 


9* 


A section  of  the  base  of  the  Allegheny  in  which  both  the  Brook- 
ville  and  Clarion  coals  show  is  as  follows: 


Section  of  lower  part  of  Allegheny  formation  near  A.  J.  Haws  A Sons'  brick  plant , 

Coopersdale. 


Ft.  in. 


Shale,  dark.- 10+ 

Coal 1 0-4 

Shale,  black,  with  siliceous  limestone  concretions 10 

Coal 51 

Shale  and  bone 4 

Coal 1 0-5 

Shale  and  bone 0-10 

Pottsville  sandstone,  massive. 


The  thickness  of  the  Allegheny  ranges  from  220  to  290  feet.  At 
its  top  is  the  Upper  Freeport  coal;  at  its  base  the  Brookville  coal. 
The  former  occurs  almost  directly  below  the  massive  Mahoning 
sandstone;  the  latter  rests  directly  on  the  top  of  the  even  more 


24  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


massive  Pottsville — circumstances  which  in  this  particular  area  are 
helpful  in  determining  the  boundaries  of  the  formation. 

The  more  characteristic  members  of  the  Allegheny  formation 
occurring  in  the  Johnstown  quadrangle  are  the  following: 

Upper  Freeport  coal  (E). 

Upper  Freeport  limestone  member. 

Bolivar  clay  member. 

Butler  sandstone  member. 

Lower  Freeport  coal  (D). 

Lower  Freeport  limestone  member. 

Upper  Kittanning  coal  (O'). 

Johnstown  limestone  member. 

Coals  between  the  Upper  Kittanning  and  Lower  Kittanning  coals. 

Lower  Kittanning  coal  (B). 

Lower  Kittanning  clay  member. 

Kittanning  sandstone  member. 

Clarion  coal. 

B rook vi lie  coal. 

A B C D E F 


Upper  Freeport  coal. 


Lower  Freeport  coal. 


Upper  Kittanning  coal. 


Middle  Kittanr.ing  coal. 


Lower  Kittanning  coal. 


Clarion  coal. 

Brookville  coal. 

Top  of  Pottsville  formation. 

Figure  2.— Skeleton  sections  showing  coals  in  the  Allegheny  formation.  Vertical  scale,  1 inch=100  feet. 
A,  Compiled  section  near  Coopersdale;  B,  compiled  section  on  Peggvs  and  Clapboard  runs:  C,  section 
north  of  South  Fork;  D,  section  south  of  South  Fork;  E,  compiled  section  near  southern  border  of 
quadrangle;  F,  section  on  Blacklick  Creek. 

The  position  of  the  coals  with  reference  to  one  another  in  the 
different  districts  is  well  shown  in  figure  2. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  447  PLATE  IV 


A.  EXPOSURE  OF  LOWER  FREEPORT  COAL  ON  STONY  CREEK,  NEAR  TROLLEY  BRIDGE. 
The  overlying  sandstone  is  the  Butler.  The  Lower  Freeport  limestone  member  shows  below  the  coal. 


B.  COUNTRY  BANK  OF  THE  BETTER  CLASS  ON  THE  UPPER  KITTANNING  COAL  NEAR 

MINERAL  POINT 


CARBONIFEROUS  SYSTEM. 


25 


DETAILED  DESCRIPTION. 

Upper  Freeport  coal. — The  Upper  Freeport  coal  lies  at  the  top  of 
the  Allegheny  formation,  almost  directly  below  the  massive  Mahoning 
sandstone  member  and  from  220  to  290  feet  above  the  top  of  the 
Pottsville  formation,  or,  as  it  is  locally  called,  the  “Conglomerate 
Rock.”  It  is  known  in  the  Johnstown  district  as  the  Upper  Free- 
port or  E bed  but  most  commonly  as  the  Coke  Yard  coal.  In  the 
South  Fork  district  it  is  called  the  Lemon  or  Four-foot  coal.  Its 
chemical  and  physical  characteristics  will  be  discussed  in  subsequent 
parts  of  this  bulletin,  as  will  be  the  case  with  the  other  workable 
coals. 

Upper  Freeport  limestone  member. — In  the  region  near  South  Fork 
the  Upper  Freeport  limestone  appears  in  the  section.  A short  dis- 
tance east  of  Ehrenfeld  it  is  well  exposed  in  some  recent  excavations 
along  the  Pennsylvania  Railroad,  in  which  it  ranges  from  1 J to  3 feet 
in  thickness.  It  is  a gray  limestone  and  very  irregularly  bedded. 
(See  section,  p.  65.) 

Bolivar  clay  member. — A flint  clay  lying  a few  feet  below  what  is 
regarded  as  the  Upper  Freeport  coal  was  seen  at  a few  places  in  the 
valley  of  Mardis  Run,  near  the  northwestern  edge  of  the  quadrangle. 
This  clay  probably  corresponds  with  the  Bolivar  fire  clay  of  the  region 
to  the  southwest.  Two  feet  of  clay  was  seen  at  one  point  on  the 
outcrop,  and  the  bed  may  possibly  be  thicker. 

Butler  sandstone  member. — In  some  places  on  Stony  Creek  a very 
massive  sandstone  20  feet  thick  was  observed  lying  directly  over  the 
Lower  Freeport  or  D coal.  (See  PL  IV,  A.)  This  corresponds  in 
position  to  the  Butler  or  “ Upper  Freeport”  sandstone.  It  is  very 
local  in  its  development. 

Lower  Freeport  coal. — The  Lower  Freeport  or  D coal  is  known  about 
Johnstown  as  the  Limestone  bed  from  a 2 to  3 foot  bed  of  limestone 
occurring  within  a foot  of  its  base.  In  position  it  ranges  from  45  to  70 
feet  below  the  Upper  Freeport  coal.  (See  PL  IV,  A.) 

Lower  Freeport  limestone  member. — The  Lower  Freeport  limestone 
occurs  either  directly  below  or  within  a foot  of  the  base  of  the  Lower 
Freeport  coal,  the  slight  interval  as  a rule  being  filled  with  black  shale. 
This  limestone  shows  in  Plate  IY,  A. 

Upper  Kittanning  ( C ')  coal. — The  next  lower  horizon  of  importance 
is  the  Upper  Kittanning  or  C'  coal,  known  near  Johnstown  as  the 
Cement  coal.  It  is  an  important  coal  near  Johnstown  and  Windber, 
and  in  fact  is  one  of  the.  most  persistent  and  valuable  coals  in  the 
quadrangle.  It  occurs  from  80  to  105  feet  below  the  Upper  Freeport, 
though  near  South  Fork  this  interval  is  less.  Above  the  Upper 
Kittanning  coal,  near  Johnstown  and  to  the  west  on  Dalton  Run, 
some  of  the  sections  show  one  and  some  two  small  coals.  These 
sections  follow. 


26  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Section  of  Upper  Kittanning  coal  at  mouth  of  Rolling  Mill  mine  of  Cambria  Steel  Com- 
pany, Johnstown,  Pa. 


Ft.  in. 

Sandstone,  thin  bedded 3 

Coal 2-4 

Sandstone,  thin  bedded  and  laminated 8 

Shale 6 

Coal,  Upper  Kittanning  (O') 3 

Shale 1 

Limestone 44- 

Shale  or  fire  clay 2-4 


Section  of  Upper  Kittanning  (C/)  coal  on  Dalton  Run. 


Shale.  Ft.  in. 

Coal 4 

Shale 10 

Coal 4 

Shale 3 

Coal 4 

Shale  or  clay 24- 


Limestone  bowlders. 


Johnstown  limestone  member. — About  Johnstown  the  Upper  Kittan- 
ning coal  is  underlain  by  a limestone  which  may  prove  suitable  for 
the  manufacture  of  cement.  This  cement  bed  is  best  developed  along 
Stony  Creek  and  may  be  seen  to  advantage  in  the  cuts  on  the  Balti- 
more and  Ohio  Railroad  north  of  Kring,  where  it  is  6 feet  thick  and  is 
separated  from  the  coal  by  8 to  12  inches  of  shale.  Along  the  spur 
track  leading  from  the  north  end  of  the  tunnel  into  the  Valley  Coal 
and  Stone  Company’s  mines  it  is  also  conspicuous  but  is  slightly 
thinner.  An  analysis  of  this  cement  rock  is  given  on  page  128.  It 
is  shown  in  Plate  VII,  A (p.  48). 

Coals  between  the  Upper  and  Lower  Kittanning  coals. — In  several 
of  the  sections  south  of  Johnstown  a coal  bed  occurs  from  17J  to  20 
feet  below  the  base  of  the  Upper  Kittanning  coal.  This  coal  is  very 
thin,  in  most  places  measuring  less  than  6 inches.  It  may  be  seen  in 
the  bluffs  near  the  Citizens  Eighth  Ward  mine  and  in  the  cut  on  the 
Baltimore  and  Ohio  Kailroad  north  of  Kring.  At  the  latter  place 
another  coal  7\  inches  thick  appears  in  the  section  13  feet  below  the 
upper  thin  coal  and  about  31  feet  below  the  base  of  the  Upper  Kittan- 
ning bed.  What  is  probably  the  upper  of  these  two  coals  appears  in 
many  of  the  drill  records  from  the  Wiimore  Basin,  and  both  are  per- 
sistent in  the  section  along  the  main  line  of  the  Pennsylvania  Railroad 
east  of  East  Conemaugh.  In  the  latter  region,  however,  the  lower  coal, 
which  it  is  thought  must  be  the  representative  of  the  Middle  Kittanning 
(C)  coal,  lies  45  to  50  feet  below  the  base  of  the  Upper  Kittanning — a 
distance  greater  than  at  Kring.  Near  the  brick  plant  of  A.  J.  Haws 
& Sons  (Limited),  at  Coopersdale,  what  is  tentatively  regarded  as 
the  Middle  Kittanning  occurs  25  feet  above  the  Lower  Kittanning  bed. 


CARBONIFEROUS  SYSTEM. 


27 


Lower  Kittanning  coal. — The  next  lower  coal — the  Lower  Kittanning, 
Miller,  White  Ash,  or  B coal — is  the  most  persistent  and  valuable  bed 
in  the  area.  It  usually  lies  approximately  145  to  200  feet  below  the 
Upper  Freeport  coal  and  from  about  65  to  100  feet  above  the  top  of 
the  Pottsville. 

Lower  Kittanning  clay  member. — The  Lower  Kittanning  clay  is  the 
most  valuable  plastic  clay  in  the  area.  It  usually  underlies  the  lower 
bench  of  the  Lower  Kittanning  coal,  from  which  it  may  be  separated 
by  a few  inches  of  shale.  In  the  absence  of  the  lower  bench  of  coal 
it  sometimes  occurs  below  the  main  coal  itself,  being  separated  from 
it  by  3 to  4 inches  of  bone  or  shale.  (See,  further,  pp.  117-118,  123.) 

Kittanning  sandstone  member. — On  the  Baltimore  and  Ohio  Rail- 
road, between  Foustwell  and  the  mouth  of  Paint  Creek,  on  the  west 
flank  of  the  Ebensburg  anticline,  the  Pottsville  and  the  beds  below 
the  Lower  Kittanning  coal  are  well  exposed.  Near  the  water  tank 
and  culvert  nearly  a mile  east  of  the  bridge  over  Stony  Creek  the 
following  section  was  measured: 

Section  of  the  lower  part  of  the  Allegheny  formation , east  of  Foustwell. 


Base  of  Lower  Kittanning  coal.  Ft.  In. 

Fire  clay 4 8 

Sandstone,  laminated 9 8 

Sandstone,  massive 40 

Shale 2 

Coal 6 

Shale,  black 6 

Coal ‘ 2 7 

Shale 10 

Sandstone,  blue,  laminated s 5 

Pottsville  sandstone,  massive. 


Brookville  and  Clarion  coals. — Between  the  Lower  Kittanning  coal 
and  the  top  of  the  Pottsville  formation  are  found  either  one  or  two 
coals.  The  coal  noted  in  the  preceding  section  is  one  of  these,  possi- 
bly the  upper  or  Clarion  bed;  where  the  section  was  taken  it  is  of 
workable  thickness.  Both  coals  appear  at  the  roadside  near  A.  J. 
Haws  & Sons’  brick  plant,  west  of  Coopersdale.  (For  section,  see 
p.  23.)  The  lower  coal,  consisting  of  two  benches,  is  the  Brook- 
ville; the  higher  is  regarded  as  the  Clarion.  Representatives  of  these 
lower  coals  are  found  near  Twin  Rocks. 

POTTSVILLE  FORMATION. 

The  Pottsville,  where  most  plainly  developed  in  the  Johnstown 
quadrangle,  consists  of  three  members — an  upper  and  a lower  sand- 
stone, known  respectively  as  the  Homewood  and  Connoquenessing 
sandstone  members,  and  an  intervening  shale  (containing  a coal  bed), 
known  as  the  Mercer  shale  member.  With  these  is  associated  an 
important  flint  clay. 


28  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

A section  of  the  Pottsville  along  Stonj-  Creek,  in  part  off  the 
southern  edge  of  the  quadrangle,  is  as  follows: 

Section  of  Pottsville  formation  in  and  near  Johnstown  quadrangle. 


Feet. 

Sandstone,  massive  (Homewood) 65-90 

Shale,  black,  and  clay  (Mercer) 11 

Sandstone,  massive  (Connoquenessing) 95-105 


This  gives  a total  thickness  to  the  Pottsville  of  about  170  feet. 
Between  South  Fork  and  Mineral  Point  the  thickness  of  the  Home- 
wood  member,  where  it  could  best  be  observed,  is  only  about  35  feet, 
indicating  a thinning  to  the  east;  the  thickness  of  the  whole  forma- 
tion, however,  remains  at  about  170  feet.  In  the  South  Fork  district 
the  Mercer  interval  contains  a valuable  flint  clay. 

The  Pottsville  is  not  always  devoid  of  coal,  as  the  section  green 
above  might  indicate.  South  of  Kring  the  Mercer  contains  a coal 
bed  whose  section  is  given  on  page  61.  At  the  B.  H.  Campbell  shale 
quarry,  on  the  Mercer  (p.  119),  coal  is  also  present. 

The  sandstones  of  the  Pottsville  are  massive  and  coarse  grained 
but  rarely  conglomeratic.  They  make  very  large  sandstone  debris, 
and  the  country  underlain  by  the  Pottsville  is  usually  wilderness. 

MISSISSIPPI  AN  SERIES. 

MATCH  CHUNK  SHALE. 

Evidences  of  an  unconformity  at  the  top  of  the  Mauch  Chunk  are 
to  be  seen  in  the  Johnstown  quadrangle.  The  Mauch  Chunk  is  well 
exposed  along  the  flanks  of  the  Ebensburg  anticlinal  axis  on  Stony 
Creek,  near  the  bridge  at  the  mouth  of  Paint  Creek,  and  also  south 
of  the  quadrangle.  It  is  also  well  shown  at  the  viaduct  along  the 
flanks  of  the  Viaduct  or  Ebensburg  anticline  (PI.  V,  A ),  farther  west 
in  the  gorge  of  Conemaugh  River,  and  on  the  sides  of  Laurel  Ridge, 
where  it  is  brought  above  drainage  level  by  the  Laurel  Ridge  anti- 
cline. The  upper  50  feet  of  this  formation  is  exposed  in  the  valley 
of  South  Branch  of  Blacklick  Creek,  near  Twin  Rocks. 

A section  of  the  upper  part  of  the  formation,  obtained  on  Stony 
Creek  about  a mile  above  the  mouth  of  Paint  Creek,  is  as  follows: 

Section  of  upper  two  members  of  Mauch  Chunk  shale  near  mouth  of  Paint  Creek . 


Ft.  in. 

Shales,  red 6-21 

Sandstone,  heavy 10  8 

Shale,  red 20 

Sandstone,  vivid  green , 3 

Shales,  red  and  green 13-15 

Shale,  green 1 

Shale,  blue-green,  sandy 5 4 

Sandstone,  green,  usually  laminated  and  cross  bedded 44-f 


U.  S.  GEOLOGICAL  SURVEY  BULLETIN  447  PLATE  V 


A.  TYPICAL  EXPOSURE  OF  MAUCH  CHUNK  SHALE  AT  THE  VIADUCT  BETWEEN  SOUTH  FORK 

AND  MINERAL  POINT. 


Note  the  alternating  thin  layers  of  sandstone  and  shale  and  the  vertical  jointing. 


B.  SHALE  QUARRY  OF  B.  H.  CAMPBELL  AT  THE  MERCER  HORIZON  NORTH  OF  SHERIDAN. 
The  rounded  bowlders  in  the  foreground  are  probably  of  Pleistocene  age. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  447  PLATE  VI 


A.  DETAILED  STRUCTURE  OF  LOYALHANNA  LIMESTONE  AT  THE  TOP  OF  THE  POCONO 
FORMATION,  EAST  OF  MINERAL  POINT. 

Weathering  has  brought  out  the  cross-bedding  of  the  rock. 


B.  LOYALHANNA  LIMESTONE,  TOP  MEMBER  OF  POCONO  FORMATION,  AT  SUMMIT  OF  EBENS- 
BURG  (VIADUCT)  ANTICLINE,  MINERAL  POINT. 


DEVONIAN  SYSTEM. 


29 


Near  the  viaduct  the  lower  green  laminated  and  cross-bedded  sand- 
stone member  given  in  the  sectiori  appears,  dividing,  as  it  were,  the 
Mauch  Chunk  into  an  upper  and  lower  shaly  member.  It  may  rep- 
resent the  Greenbrier  limestone  in  this  region.  This  sandstone  at 
the  viaduct  was  measured  in  its  entirety  and  was  found  to  be  42  feet 
thick.  The  lower  shale  division  at  the  viaduct  is  40  feet,  giving  to 
the  members  of  the  Mauch  Chunk  the  following  thicknesses: 

Section  of  Mauch  Chunk  shale  at  the  viaduct. 


Feet. 

Upper  shaly  member 60-75 

Sandstone 44+ 

Lower  shale  member 40 


Thus  the  Mauch  Chunk  in  this  quadrangle  may  be  considered 
approximately  160  feet  thick. 

POCONO  FORMATION. 

The  upper  part  of  the  Pocono  shows  in  the  bed  of  Conemaugh 
River  between  the  viaduct  and  Mineral  Point.  It  is  made  up  of  the 
Loyalhanna  limestone  member,  about  45  feet  of  which  is  here  exposed. 
(See  PI.  VI,  A and  B.)  The  entire  formation  is  above  drainage  level 
in  the  gorge  of  Conemaugh  River  west  of  Johnstown.  It  is  brought 
above  water  level  by  the  Laurel  Ridge  anticline  and  covers  part  of 
the  ridge  both  south  and  north  of  the  river.  Though  it  is  not  exposed 
so  as  to  be  measured  in  detail,  the  barometer  indicated  from  the  top 
of  the  red  Catskill  beds  to  the  red  shales  of  the  Mauch  Chunk  over- 
lying  the  Loyalhanna  limestone  a thickness  of  1,085  feet,  which  it  is 
believed  closely  approximates  the  thickness  of  this  formation  in  the 
region.  This  is  slightly  greater  than  the  figures  obtained  by  Charles 
Butts  and  the  writer®  on  the  Allegheny  Front.  There  is  no  reason 
to  suppose  that  the  Pocono  here  differs  much  from  that  on  the  Alle- 
gheny Mountain  east  of  Bennington. 

DEVONIAN  SYSTEM. 

CATSKILL  FORMATION. 

But  400  feet  of  Devonian  rocks  are  exposed  in  the  Johnstown 
quadrangle,  and  these  occur  at  the  top  of  the  Catskill,  in  the  gorge  of 
Conemaugh  River  where  it  is  crossed  by  the  Laurel  Ridge  anticlinal 
axis.  The  Catskill  beds  are  prevailingly  red  and  green  shales  and 
red  sandstones  and  color  the  soil  a distinct  red.  The  upper  part  of 
the  formation  was  measured  by  the  writer  as  follows: 


a Ebensburg  folio  (No.  133),  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1905,  p.  3. 


30  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Section  of  upper  portion  of  CatsJcill  formation  on  Conemaugh  River. 

Feet. 


Sandstone,  chocolate  and  reddish 45 

Shale,  red 20 

Sandstone,  chocolate-colored 5 

Shales,  chocolate  and  vivid  green 40+ 


STRUCTURE. 

MODE  OF  REPRESENTATION. 

The  inclination  of  the  beds  to  a horizontal  plane,  or  the  dip,  as 
it  is  commonly  called,  is  measured  in  the  field  by  means  of  a cli- 
nometer where  the  inclination  is  great  enough  to  permit  it.  In  but 
few  localities  in  the  Johnstown  quadrangle,  however,  are  the  dips 
sufficient  to  allow  this  mode  of  measurement.  Where  it  is  not  appli- 
cable continuous  road  sections  are  run  and  the  beds  are  correlated 
from  hillside  to  hillside.  When  the  elevation  above  mean  sea  level 
of  a sandstone,  coal,  or  limestone  on  one  hill  and  its  elevation  a mile 
or  so  away  have  been  found,  the  rise  or  fall  of  this  particular  bed  in 
feet  per  mile  is  at  once  obtained.  By  connecting  points  of  equal 
elevation  on  any  selected  bed  the  contour  lines  for  that  bed  are 
drawn.  On  the  map,  Plate  I,  the  contour  interval  is  50  feet  and  all 
points  on  the  plane  selected  (the  base  of  the  Lower  Kittanning  or  B 
coal)  that  are  multiples  of  50  are  connected  by  light-brown  lines. 

The  base  of  the  Lower  Kittanning  coal  was  selected  as  the  bed  on 
which  to  draw  structure  contours  in  the  Johnstown  quadrangle 
because  this  is  commercially  the  most  important  coal  and  the  most 
persistent.  Moreover,  its  relations  to  the  beds  both  above  and  below 
it  are  fairly  well  known. 

To  draw  contours  on  the  bed  where  it  is  above  drainage  level  and 
is  worked  is  easy,  for  it  is  necessary  simply  to  obtain  its  elevation 
from  point  to  point  where  it  outcrops  and  then  to  connecting  points 
of  equal  elevation.  But  where  the  coal  fails  to  appear  above  drain- 
age level  other  means  of  determining  its  elevation  have  to  be  em- 
ployed, and  its  distance  below  other  known  beds  that  do  appear  must 
be  used  as  a basis  for  calculation,  it  being  assumed,  of  course,  that 
this  distance  is  constant  within  the  areas  where  this  method  is 
employed.  Conversely,  where  the  dips  are  so  great  as  to  carry  the 
horizon  of  the  coal  above  the  hilltops  its  interval  above  known 
beds  must  be  used.  When  the  latter  two  methods  are  employed 
in  contouring  great  precision  is  not  obtainable,  as  intervals  are  sub- 
ject to  variation  in  any  region  and  are  known  to  vary  greatly  within 
comparatively  short  distances  in  the  Johnstown  quadrangle.  Fur- 
thermore, most  of  the  elevations  in  this  work  are  obtained  by 
means  of  the  aneroid  barometer,  which,  as  is  well  known,  is  liable  to 
sudden  variations  and  has  to  be  constantly  checked  against  spirit- 
leveled  elevations. 


STRUCTURE. 


31 


The  structure  contours  not  only  show  the  generalized  surface 
formed  by  the  Lower  Kittanning  coal  but  less  precisely  the  lay  of 
the  underlying  and  overlying  beds.  The  contour  interval  chosen  is 
50  feet  and  the  limit  of  error  may  be  considered  a contour  interval, 
but  where  the  beds  vary  in  thickness  it  may  be  more  than  this. 
This  mode  of  representing  the  structure  makes  it  possible  to  estimate 
approximately  the  elevation  of  the  top  of  the  Lower  Kittanning  coal 
where  it  is  below  the  surface  at  a given  point,  and  hence  to  find  its 
depth  below  the  surface  at  that  point ; furthermore,  if  the  intervals 
of  other  coals  either  above  or  below  the  Lower  Kittanning  are  known, 
their  depth  at  any  particular  point  may  be  readily  computed. 

STRUCTURE  IN  THE  JOHNSTOWN  QUADRANGLE. 

GENERAL  STATEMENT. 


The  beds  described  under  the  heading  “ Stratigraphy”  (pp.  14-30) 
are  involved  in  a series  of  parallel  folds  having  a general  northeast- 
southwest  trend  and  extending  completely  across  the  area  in  a series 


Figure  3.— Sketch  showing  (a)  the  great  irregularity  in  detail  of  the  structure  in  some  parts  of  the  Johns- 
town quadrangle  and  (6)  the  marked  regularity  in  detail  in  other  parts.  In  6 the  5-foot  contour  lines  are 
omitted  to  avoid  crowding,  but  were  they  inserted  the  regularity  would  appear  almost  as  pronounced. 


of  waves  from  the  southeast  to  the  northwest  part  of  the  quadrangle. 
The  structure  as  worked  out  differs  in  some  particulars  from  that 
described  by  the  Second  Survey  of  Pennsylvania,  the  most  notable 
difference  perhaps  being  in  the  offset  of  the  Johnstown  Basin  to  the 


32  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

east  near  Johnstown  (PL  I).  In  the  map  of  the  Second  Survey  the 
axis  of  the  Johnstown  syncline  or  basin  is  represented  as  being  west 
of  the  South  Fork  of  Bens  Creek;  it  is  believed  that  it  really  lies 
farther  to  the  east. 

Viewed  broadly,  the  structure  is  very  regular  in  the  Johnstown 
quadrangle,  as  will  be  seen  from  the  structural  contour  map  (PL  I). 
In  detail  it  may  be  decidedly  irregular.  (See  fig.  3.) 

The  structural  features  in  the  Johnstown  quadrangle,  beginning  in 
the  southeast  corner  and  proceeding  to  the  northwest,  are — 

Wilmore  syncline. 

Viaduct  or  Ebensburg  anticline. 

Johnstown  syncline. 

Laurel  Ridge  anticline. 

Westover  or  Barnesboro  syncline. 

In  the  reports  of  the  Second  Geological  Survey  of  Pennsylvania 
the  Wilmore  and  Johnstown  basins  were  designated  subbasins  and 
were  considered  to  constitute  part  of  the  first  bituminous  coal  basin. 
The  Viaduct  anticline  was  called  a subaxis  and  the  Laurel  Ridge 
anticline  was  designated  the  first  grand  axis  of  the  bituminous  coal 
regions.®  DTnvilliers  6 somewhat  changed  the  usage,  .as  he  speaks 
of  the  first  and  second  basins,  referring  to  the  Wilmore  and  Johns- 
town basins,  respectively.  The  terms  syncline  and  basin  or  trough 
are  of  course  synonymous,  as  are  also  the  terms  anticline  and  arch. 

DETAILED  DESCRIPTION. 

Wilmore  syncline. — The  Wilmore  Basin  or  syncline  is  so  called 
from  the  town  of  Wilmore,  situated  on  the  Pennsylvania  Railroad  a 
short  distance  east  of  Summerhill,  in  the  Ebensburg  quadrangle.  It 
is  a comparatively  long  and  narrow  synclinal  trough  parallel  with  and 
west  of  the  Allegheny  Front.  The  position  of  the  axis  of  the  basin  is 
definitely  fixed  near  the  town  of  Wilmore  by  the  opposing  dips  of  the 
rocks  along  the  old  track  of  the  Pennsylvania  Railroad.  As  indi- 
cated on  Plate  I,  the  axis  enters  the  Johnstown  quadrangle  northeast 
of  the  old  reservoir  site  on  South  Fork  of  Conemaugh  River  and  con- 
tinues southeast,  passing  near  the  town  of  Elton.  It  leaves  the 
quadrangle  in  a line  almost  coincident  with  the  South  Fork  branch  of 
the  Pennsylvania  Railroad.  On  the  southeast  side  of  this  axis  the 
beds  dip  northwest,  and  on  the  northwest  side  the  beds  dip  southeast. 
In  the  quadrangle  all  the  beds  along  the  axis  dip  northeast,  as  the 
axis  plunges  in  that  direction.  The  rise  of  the  beds  to  the  southwest 
is  rapid,  amounting  to  900  feet  in  a distance  of  16  or  17  miles,  so  that 
the  Lower  Kittanning  coal,  which  is  between  800  and  900  feet  above 
the  sea  and  hence  far  below  drainage  level  in  the  center  of  the  basin, 


a Second  Geol.  Survey  Pennsylvania,  Rept.  H2,  pp.  xxix,  25,  26. 
i>  Summary  Final  Rept.  Geol.  Survey  Pennsylvania,  1895,  p.  2219. 


I 


STRUCTURE.  33 

outcrops  at  an  elevation  of  about  1,700  feet  at  the  mines  about 
Windber. 

Viaduct  anticline. — The  Viaduct  or  Ebensburg  anticline  is  the  next 
structural  feature  to  the  west.  Its  axis  has  a general  northeast- 
southwest  direction,  but  swerves  slightly  to  the  southeast  and  then 
again  to  the  southwest  in  the  part  of  the  quadrangle  south  of  Cone- 
maugh  River.  This  offset,  however,  is  not  at  all  marked. 

The  Lower  Kittanning  coal  and  associated  beds,  so  deeply  buried 
in  the  center  of  the  Wilmore  Basin,  rise  rapidly  and  with  great  regu- 
larity to  the  west  and  outcrop  in  the  valley  of  Conemaugh  River  at 
South  Fork.  From  its  deepest  point  in  the  Wilmore  syncline  the 
coal  rises  more  than  1,000  feet  to  its  highest  point  on  the  summit  of 
the  Viaduct  or  Ebensburg  anticline.  The  lowest  bed  brought  above 
drainage  level  by  this  rise  is  the  top  member  of  the  Pocono  forma- 
tion (the  Loyalhanna  limestone  member),  which  outcrops  along  the 
summit  of  the  arch,  between  the  viaduct  and  Mineral  Point.  (See 
PI.  VI,  A and  B.) 

Johnstown  Basin. — The  Johnstown  Basin  or  syncline,  which  is  the 
next  structural  feature  to  the  west,  comprises  the  area  between  the 
Viaduct  and  Laurel  Ridge  anticlinal  axes.  It  is  really  made  up  of 
two  basins  in  this  quadrangle,  one  in  Cambria  and  one  in  Somerset 
County.  It  has  a general  northeast-southwest  course  but  is  sharply 
offset  to  the  east  in  the  vicinity  of  Johnstown.  (See  PL  I.)  The 
axis  in  Somerset  County  trends  in  the  usual  northeast-southwest 
course.  The  dip  of  the  beds  on  the  east  side  of  the  basin  is  compara- 
tively gentle,  the  fall  being  approximately  900  feet  in  9 miles,  or  at 
the  rate  of  100  feet  per  mile  from  the  summit  of  the  Viaduct  anti- 
cline at  the  viaduct  to  the  deepest  part  of  the  basin  north  of  Cone- 
maugh River.  In  the  southern  part  of  the  quadrangle  the  correspond- 
ing drop  is  only  700  feet.  On  the  west  side  of  the  basin  the  rise  of  the 
beds  to  the  Laurel  Ridge  axis  is  sharp — between  2,000  and  2,100  feet 
in  a distance  of  9 miles  along  Conemaugh  River — producing  the  maxi- 
mum dips  in  the  quadrangle.  In  addition  to  their  inclination  from 
the  northwest  and  southeast  to  the  center  of  the  basin,  the  beds  north 
of  Conemaugh  River  dip  gently  to  the  northeast.  The  Johnstown 
synclinal  axis  and  the  Ebensburg  anticlinal  axis  approach  each  other 
near  the  northeast  corner  of  the  quadrangle. 

Laurel  Ridge  anticline. — The  Laurel  Ridge  anticline  is  the  major 
structural  feature  in  the  Johnstown  quadrangle,  and,  as  stated  on 
page  32,  it  is  the  “ first  grand  axis”  as  described  by  the  Second 
Geological  Survey  of  Pennsylvania.  It  crosses  Conemaugh  River 
about  midway  between  Conemaugh  Furnace  and  Coopersdale  and 
passes  to  the  northeast,  crossing  South  Branch  of  Blacklick  Creek  a 
little  over  a mile  southeast  of  Twin  Rocks.  Where  the  axis  of  the 


69516°— Bull.  447—11 3 


34  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

fold  crosses  the  valley  of  Conemaugh  River  the  lowest  beds  in  the 
quadrangle — the  red  shales  and  sandstones  of  the  Catskill  formation, 
aggregating  400  feet  or  more  above  drainage  level — are  exposed. 
The  fold  pitches  sharply  to  the  northeast,  and  the  Pocono  formation, 
which  caps  the  hills  where  the  axis  crosses  Conemaugh  River,  is 
below  drainage  level  where  it  crosses  South  Branch  of  Blacklick 
Creek  near  Twin  Rocks,  dropping  in  this  distance  at  least  1,000  feet. 
As  stated  in  the  description  of  the  Johnstown  Basin,  the  beds  along 
the  eastern  flank  of  the  Laurel  Ridge  anticline  rise  between  2,000 
and  2,100  feet  in  a distance  of  9 miles.  The  fall  in  the  beds  west  of 
the  anticlinal  axis  to  the  Barnesboro  or  Westover  Basin  is  at  about 
the  same  rate.  The  anticline  is  therefore  symmetrical. 

No  beds  of  coal  are  present  at  the  summit  of  the  ridge  and  none 
occur  below  its  surface  until  Blacklick  Creek  is  approached.  The 
coals  have,  so  to  speak,  been  carried  out  into  the  air  by  the  rise  in 
the  beds  on  either  side  of  the  anticlinal  axis. 

Barnesboro  or  Westover  syncline. — The  basin  west  of  the  Laurel 
Ridge  anticline  is  termed  the  Westover  Basin  in  the  Pennsylvania 
Geological  Survey  reports.  More  recently  it  has  been  called  the 
Barnesboro  Basin  by  members  of  the  United  States  Geological 
Survey.0  The  axis  of  the  basin  enters  the  Johnstown  quadrangle 
near  the  line  between  Cambria  and  Indiana  counties,  passes  through 
or  very  near  Wehrum,  and  leaves  the  quadrangle  as  indicated  on 
Plate  I.  From  the  axis  of  this  basin  the  beds  rise  gently  to  the 
axis  of  the  Nolo  anticline,  which  just  cuts  the  northwest  corner  of 
the  quadrangle. 

Minor  structures. — Besides  the  principal  folds,  there  are  many 
minor  folds  in  the  rocks  of  the  quadrangle.  A small  arch  or  anti- 
cline is  exposed  along  Little  Conemaugh  River  about  a mile  east  of 
Conemaugh  station.  From  this  point  westward  to  the  Johnstown 
station  there  are  many  minor  fluctuations,  all  exposed  along  the  main 
line  of  the  Pennsylvania  Railroad.  Between  Millville  and  Coopers- 
dale  there  is  a distinct  anticline.  Thus  it  appears  that  the  main 
broad  Johnstown  syncline  has  been  subjected  to  many  minor  plica- 
tions. It  has  been  thought  by  some  mining  men  that  to  these  lesser 
folds  about  Franklin  and  along  Clapboard  Run  is  due  the  so-called 
faulting  which  the  coal  exhibits  in  this  region.  The  erratic  behavior 
of  the  Lower  Kittanning  coal  in  this  locality  may  possibly  be  due 
in  part  to  this  cause,  but  the  irregularities  seen  by  the  writer  are  not 
faults  as  this  term  is  used  in  the  geologic  sense,  but  are  rather  broad 
rolls  which  seem  to  have  squeezed  out  the  coal.  In  some  places  the 
conditions  during  sedimentation  were  such  that  coal  was  not  depos- 
ited or,  if  deposited,  was  afterward  removed. 


a Campbell,  M.  R.,  and  Clapp,  F.  G.,  in  an  unpublished  manuscript  relating  to  the  Barnesboro  quad- 
rangle, which  lies  north  of  the  Johnstown  quadrangle. 


COAL. 


35 


MINERAL  RESOURCES. 

INTRODUCTION. 

The  mineral  resources  of  the  Johnstown  quadrangle  are  coal,  flint 
and  plastic  clay,  shales,  limestone  and  cement  material,  building 
stone,  glass  sand,  and  iron  ore.  Because  of  the  great  importance  of 
coal  and  clay  they  will  be  treated  (1)  in  a broad  way  for  the  sake 
of  the  general  reader  who  may  be  interested  in  the  area  as  a whole 
but  not  in  any  particular  portion  of  it,  and  (2)  in  detail  by  districts. 
The  remaining  resources— limestone  and  cement  material,  building 
stone,  glass  sand,  and  iron  ore — will  be  treated  as  a whole,  as  their 
description  by  districts  would  involve  needless  repetition. 

COAL. 

GENERAL  DESCRIPTION. 

UPPER  FREEPORT  COAL. 

The  highest  important  coal  in  the  Johnstown  quadrangle  is  known 
as  the  Upper  Freeport.  It  is  used  as  a domestic  and  steam  fuel  about 
Johnstown  and  South  Fork  and  supplies  some  of  the  brick  plants  at 
Johnstown.  It  gives  satisfactory  results,  particularly  when  used  in 
locomotives.  It  is  not  coked  in  this  quadrangle,  though  at  Cresson, 
Gallitzin,  and  Bennington  it  gives  satisfactory  results  in  beehive 
ovens.  In  the  by-product  ovens  of  the  Cambria  Steel  Company  at 
Franklin,  near  Johnstown,  it  was  found  to  be  unsuitable  owing  to 
expansion,  which  quickly  ruined  the  ovens  and  made  it  very  difficult 
to  force  out  the  charge  after  it  was  coked.  The  analyses  of  this  coal 
as  given  on  page  40  show  it  to  be  a high-carbon  coal  with  very  low 
moisture  content.  The  ash,  especially  in  the  Johnstown  Basin,  is 
high;  its  sulphur  content,  ranging  from  2 to  2\  per  cent,  is  also  rather 
high. 

LOWER  FREEPORT  COAL. 

The  Lower  Freeport  or  D coal  is  of  workable  thickness  about  Johns- 
town, and,  though  not  exploited  at  present,  it  will  probably  become 
one  of  the  important  coals  of  the  Johnstown  district.  Its  percentage 
of  carbon  is  high. 

UPPER  KITTANNING  (c')  COAL. 

The  Upper  Kittanning  or  C'  coal  is  one  of  the  most  valuable  beds 
about  Johnstown  and  its  suburbs,  where  it  is  known  as  the  Cement 
bed.  To  the  south,  about  Windber,  prospecting  has  shown  it  to 
be  even  thicker  than  about  Johnstown.  As  a steaming  coal  it  is 
probably  equal  if  not  superior  to  any  other  coal  in  the  Johnstown 


36  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Basin,  and  the  recent  demand  for  it  has  been  greater  than  the 
supply.  The  six  analyses  (p.  40)  show  a high-carbon  coal  with 
correspondingly  low  volatile  matter.  The  moisture  is  low,  but  the 
ash  and  sulphur  are  rather  high.  The  coal  mined  from  this  bed  at 
Franklin  mine  No.  1 of  the  Cambria  Steel  Company  is  washed  and 
coked  at  the  Franklin  plant.  It  makes  a coke  of  good  grade,  but 
owing  to  its  low  volatile  matter  it  is  not  considered  so  well  adapted 
for  beehive  ovens  as  some  of  the  richer  gas  coals  of  the  districts  farther 
west.  In  view  of  the  cost  of  shipping  coke  from  the  region  about 
Connellsville  and  Pittsburg,  it  is  cheaper  to  wash  and  coke  this  coal 
on  the  ground.  The  coal  is  worked  also  in  a small  way  near  South 
Fork. 

LOWER  KITTANNING  (MILLER)  COAL. 

CHARACTER  AND  IMPORTANCE. 

The  next  lower  coal  of  importance  in  this  area  is  the  Lower  Kittan- 
ning or  B coal,  also  widely  known  as  the  Miller  seam.  This  is  the 
most  persistent  of  the  valuable  coals  of  the  area.  From  the  analyses 
on  pages  40-42  it  will  be  seen  that  its  fixed  carbon  ranges  from  68 
per  cent  in  sample  No.  24,  collected  at  Welirum,  Indiana  County,  to 
more  than  78  per  cent  in  samples  collected  at  South  Fork.  Its  volatile 
matter  ranges  from  14  to  19  per  cent.  Its  moisture  is  low;  only  a 
few  analyses  show  more  than  3 per  cent  and  in  none  of  them  does  it 
exceed  4 per  cent.  The  ash  and  sulphur  exhibit  considerable  varia- 
tion, as  might  naturally  be  expected  in  view  of  the  wide  extent  of  the 
territory  from  which  the  samples  were  collected.  The  samples  from 
South  Fork  have  the  lowest  content  both  in  sulphur  and  ash  and  show 
the  excellent  character  of  the  Lower  Kittanning  bed  in  this  part  of 
the  Wilmore  Basin.  As  a steam  coal  it  ranks  among  the  very  best 
in  western  Pennsylvania,  the  coal  mined  about  South  Fork  probably 
equaling  any  other  ste^am  coal  in  this  part  of  the  State.  As  bearing 
on  this  point  the  following  table  has  been  prepared,  showing  its  posi- 
tion among  the  120-odd  coals  tested  at  the  fuel-testing  plant  of  the 
United  States  Geological  Survey  at  St.  Louis,  Mo.,  since  the  summer 
of  1904.a  The  column  recording  the  number  of  pounds  of  water 
evaporated  by  1 pound  of  dry  coal  from  and  at  a temperature  of 
212°  F.  gives  the  comparative  results  of  the  coals  tested  so  far  as 
these  relate  to  their  commercial  value. 


a Bull.  U.  S.  Geol.  Survey  No.  261,  1905,  and  No.  290,  1906. 


COAL. 


37 


Chemical  composition  and  steaming  values  of  typical  Appalachian  coals. 


Location. 

Num- 
ber of 
tests 
made. 

Aw 

Mois- 

ture. 

erage  chem 

Volatile 

matter. 

lical  com 

Fixed 

carbon. 

positio 

Ash. 

in. 

Sul- 

phur. 

Average 
pounds  of 
water  evap- 
orated 
from  and  at 
212°  F.  per 
pound  of 
dry  coal. 

Page,  Fayette  County,  W.  Va 

2 

4.06 

30.  35 

61.54 

4.05 

0.90 

10. 545 

Do 

1 

2. 85 

30. 13 

64.  78 

2.  24 

1.06 

10. 52 

McDonald,  Fayette  County,  W.  Va 

2 

2.75 

20.  59 

70.05 

6.  61 

.98 

10.36 

Big  Black  Mountain,  Harlan  County,  Ky 

2 

5.  06 

34.  77 

56.  31 

3.  86 

.56 

10. 26 

Rush  Run,  Fayette  County,  W.Va 

2 

2. 12 

21.91 

70.  73 

5.  24 

.67 

10. 195 

Ehrenfeld,  Cambria  County,  Pa 

5 

2.  38 

16.  53 

74.  47 

6.62 

.95 

10. 186 

Winifrede,  Kanawha  County.  W.Va 

4 

3.  79 

35.  33 

55.  76 

5. 12 

1.11 

10. 16 

Acme,  Kanawha  County,  W.  Va 

4 

2.  93 

32.  66 

57.  64 

6.  77 

1.  23 

10. 115 

Powellton,  Fayette  County,  W.  Va 

1 

3.  42 

31. 11 

59.  47 

6.  00 

.82 

10.09 

Near  Bretz,. Preston  County,  W.Va 

3 

4.  20 

28.05 

60.  86 

6.  89 

1.28 

10.  07 

The  results  of  tests  on  the  Ehrenfeld  samples,  although  showing  a 
range  of  9.75  to  10.42  pounds  of  water  evaporated  per  pound  of  dry 
coal  used,  are  yet,  when  averaged,  among  the  very  best  obtained  at 
the  testing  plant.  Each  sample  submitted  to  the  steaming  test  was 
analyzed,  and  the  accompanying  analyses  represent  averages  of  the 
total  number  made,  as  do  the  figures  representing  the  efficiency  of 
the  coals  as  steam  producers.  It  is  of  interest  to  note  that  the 
Ehrenfeld  coal  contains  the  largest  percentage  of  fixed  carbon  and  the 
lowest  amount  of  volatile  matter  of  all  the  samples. 

Other  samples  of  the  Lower  Kittanning  coal  tested  by  the  United 
States  fuel-testing  plant  from  January  1,  1906,  to  June  30,  1907, 
include  a few  from  in  or  near  this  quadrangle.  The  results  of  these 
tests  are  given  below,  together  with  the  analyses  of  the  samples 
tested.  For  comparison  the  results  (given  above)  from  the  Ehren- 
feld coal  are  repeated. 

Chemical  composition  and  steaming  values  of  typical  Appalachian  coals. 


Average  chemical  composition. 

Average 
pounds  of 
water  evap- 
orated 
from  and  at 
212°  F.  per 
pound  of 
dry  coal. 

Location. 

Num- 
ber of 
tests 
made. 

Mois- 

ture. 

Volatile 

matter. 

Fixed 

carbon. 

Ash. 

Sul- 

phur. 

Wehrum,  Blacklick  Creek  district,  Indiana 
Countv  o 

2 

2.17 

17.5.8 

69. 81 

10.45 

4. 62 

9.19 

Lloydell,  Cambria  County  (southeast  of 
quadrangle)  b 

2 

5.00 

19.05 

66. 78 

9. 18 

1.53 

c 9. 52 

Near  Seward,  Conemaugh  Furnace  district, 
Westmoreland  County  d 

2 

3. 15 

20.55 

67.  75 

8.56 

1.79 

c 8. 90 

Ehrenfeld,-  South  Fork  district,  Cambria 
County 

5 

2. 38 

16.53 

74.  47 

6.62 

.95 

10. 186 

a Bull.  U.  S.  Geol.  Survey  No.  332,  1908,  pp.  201,  202. 

b Idem,  pp.  210, 211.  Lloydell  is  on  the  east  flank  of  the  Wilmore  Basin  and  on  the  quadrangle  to  the  east, 
c Test  made  on  briquets  from  the  coal.' 
d Bull.  U.  S.  Geol.  Survey  No.  332,  1908,  pp.  216,  217. 


38  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

The  figures  obtained  in  the  last  column  give  comparative  commer- 
cial values  which  show  the  high  grade  of  the  Lower  Kittanning  coal 
as  coal  or  in  briquet  form  in  and  near  the  quadrangle.  It  is  of  inter- 
est to  see  how  the  analysis  and  steaming  values  of  the  coal  collected 
at  Lloydell  on  the  east  flank  of  the  Wilmore  Basin  compare  with  the 
results  obtained  near  Seward  in  the  area  to  the  west.  For  the  details 
of  the  conditions  governing  these  steaming  tests  the  reader  is  referred 
to  Bulletin  332. 

COKING  TESTS. 

The  Lower  Kittanning  (Miller)  coal  is  coked,  but  it  does  not  rank 
so  high  as  a coking  coal  as  it  does  as  a steam  producer.  Tests  on 
samples  yielded  the  following  results: 


Coking  tests  on  Lower  Kittanning  coal  in  Johnstown  quadrangle. 


L 

2. 

3. 

4. 

5. 

Duration  of  test hours. . 

Size  as  used 

51 

(a) 

10.000 
5,223 
52.  23 
1,600 
16.00 
68.  23 

61 

(a) 
9,750 
5,779 
59.  27 
262 
2.69 
61.96 

54 

(*) 

12,460 
8,144 
65.  36 
332 
2.  66 
68.02 

68 

(a) 

13,070 
8,129 
62.  20 
420 
3. 21 
65.  41 

78 

(a) 

11,760 
7,350 
62.  50 
529 
4.  50 
67.00 

Coal  charged pounds. . 

Coke  produced {^’cent 

Breeze  produced {percent ' ' 

Total  yield per  cent. . 

a Finely  crushed.  & Run  of  mine. 


Analyses  of  Lower  Kittanning  coal  and  of  coke  made  from  it. 


1. 

2. 

3. 

4. 

5. 

Coal. 

Coke. 

Coal. 

Coke. 

Coal. 

Coke. 

Coal. 

Coke. 

Coal. 

Coke. 

Moisture 

3.32 

0.91 

7.19 

0. 56 

4.53 

0. 57 

3. 91 

0. 30 

6. 30 

0. 51 

Volatile  matter 

15.  56 

2.16 

17. 86 

.32 

18.  56 

.55 

16. 35 

.28 

17. 04 

.58 

Fixed  carbon 

74.29 

88. 99 

69.57 

91.10 

70.  63 

90.23 

68.30 

84.  95 

69.58 

89.85 

Ash 

6.83 

7.94 

5.  38 

8. 02 

6.  28 

8.  65 

11.44 

14.  47 

7.08 

9.06 

Sulphur 

1.12 

.91 

1.63 

1.46 

1.85 

1.54 

2.  78 

2.31 

1.34 

1.11 

1.  Raw  bituminous  coal  from  mine  No.  3,  Pennsylvania  Coal  and  Coke  Company,  Ehrenfeld,  collected 
under  supervision  of  J.  S.  Burrows.  Bull.  U.  S.  Geol.  Survey  No.  290,  1906,  p.  181. 

2 and  3.  Washed  run-of-mine  coal  from  Wehrum,  collected  under  supervision  of  John  W.  Groves.  Bull. 
U.  S.  Geol.  Survey  No.  332,  1908,  p.  203. 

4.  Raw  run-of-mine  coal  from  a mine  1|  miles  east  of  Seward,  collected  under  supervision  of  John  W. 
Groves.  Bull.  U.  S.  Geol.  Survey  No.  332,  1908,  p.  218. 

5.  Washed  run-of-mine  coal  from  same  locality  as  No.  4. 


The  results  obtained  from  the  coking  tests  were  as  follows : 

The  coke  from  Lower  Kittanning  coal  collected  at  Ehrenfeld  (No.  1) 
was  soft  and  dense,  dull  gray  in  color,  with  a heavy  black  butt.  It 
broke  in  large  and  small  chunks  and  was  difficult  to  burn.  The  cell 
structure  was  small. 

The  coke  from  the  first  test  (No.  2)  on  the  Wehrum  sample  was  soft 
and  dense  and  dull  gray  in  color.  The  high  content  in  sulphur  is 
worthy  of  note.  The  coke  from  the  second  test  (No.  3)  on  the  Wehrum 


COAL. 


39 


sample  was  light  gray  or  silvery  in  color  and  much  better  than  the 
coke  from  the  finely  crushed  coal  (No.  2).  It  also  was  high  in  sul- 
phur. The  coke  from  the  first  test  (No.  4)  on  the  sample  collected  1 \ 
miles  east  of  Seward  was  light  gray  or  silvery  in  color  and  was  soft 
and  dense,  with  high  ash  and  sulphur.  The  coke  from  the  second  test 
(No.  5)  was  gray  in  color;  washing  produced  no  change  in  its  physical 
appearance  though  it  reduced  the  ash  and  sulphur  slightly.  As  in 
the  test  No.  4,  the  coke  was  soft  and  dense. 

It  may  be  added  that  the  yield  of  coke  in  all  the  above  tests  is  high. 
The  coal  mined  at  Franklin  (analysis  11,  p.  40)  is  coked  by  the  Cam- 
bria Steel  Company  in  by-product  ovens  for  use  in  the  company’s 
plant  near  Johnstown  and  gives  satisfactory  results.  The  coal  is 
washed  before  coking,  thereby  adding  to  the  cost,  but  even  with  this 
additional  expense  it  is  found  cheaper  to  coke  this  coal  on  the  ground 
than  to  buy  coke  of  better  quality  from  the  Connellsville  region. 
Tests  have  been  made  by  the  Cambria  Steel  Company  with  the  coal 
mined  from  this  bed  about  Ehrenfeld,  and  the  resulting  coke  proved 
well  adapted  to  metallurgical  purposes.  The  yield  also  was  satisfac- 
tory. The  coal  mined  at  Nanty  Glo  from  this  bed  has  been  tested 
in  beehive  ovens  at  Gallitzin.  It  produced  coke  of  good  structure 
but  of  a rather  dull  appearance.  As  w~as  to  be  expected,  an  insuffi- 
cient amount  of  sulphur  was  volatilized.  At  Bennington  this  coal, 
like  the  Upper  Freeport,  shows  a higher  content  in  volatile  matter 
than  it  does  about  South  Fork  and  Johnstown.  The  Lackawanna 
Coal  and  Coke  Company  has  experimented  with  it  about  Wehrum, 
but  the  washeries  have  been  shut  down  and  the  results  of  the  coking 
tests  were  not  learned.  The  results  of  Survey  tests  have  already 
been  given  (p.  38).  The  Vinton  Colliery  Company  has  erected  a by- 
product plant  at  Vintondale,  and  in  1907  a considerable  part  of  the 
coal  mined  from  colliery  No.  6 was  coked. 

MISCELLANEOUS  TESTS. 

Other  tests  have  been  made  on  the  Lower  Kittanning  coal,  such 
as  producer-gas  tests,  washing  tests,  cupola  tests,  and  briquetting 
tests.  The  details  connected  with  these  are  given  where  this  coal  is 
considered  in  the  different  districts  (pp.  71-76,  83-88,  98-100). 


LOWER  ALLEGHENY  COALS. 

The  coals  below  the  Lower  Kittanning  have  not  been  extensively 
developed  in  this  area.  At  South  Fork  a bed  lying  about  60  feet 
below  the  Miller  coal  and  known  locally  as  the  Dirty  A or  Six-foot 
seam  has  been  opened.  It  is  possible  that  this  corresponds  to  the 
Brookville  (A)  coal  of  the  Allegheny  Valley.  It  has  a composition 
indicated  by  analysis  36  on  pages  41-42,  and  from  the  high  ash  and 


40  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

sulphur  content,  aggregating  more  than  15  per  cent,  deserves  the 
name  which  is  often  applied  to  it.  In  other  respects  the  analysis 
corresponds  with  those  of  other  coals  of  the  area,  being  relatively 
high  in  fixed  carbon  and  low  in  volatile  matter. 


COMPOSITION  OF  THE  COALS. 

The  coals  of  the  Johnstown  quadrangle  belong  to  the  soft,  lustrous, 
semibituminous  variety.  They  are  best  adapted  for  steaming  and 
.domestic  purposes,  but  some  of  them  make  also  an  excellent  coke. 
They  are  classed  as  smokeless  coals  because  of  their  small  content 
of  volatile  hydrocarbons.  They  are  uniformly  high  in  carbon  and 
contain  small  amounts  of  volatile  matter  and  moisture.  Their  ash 
and  sulphur  contents  are  variable  but  in  general  terms  high  compared 
with  other  Appalachian  coals — for  instance,  those  of  West  Virginia 
and  eastern  Kentucky.  Some  analyses  of  samples  collected  accord- 
ing to  present  Survey  methods  are  listed  below. 


Analyses  of  coal  samples  from  Johnstown  quadrangle , Pennsylvania. a 


Upper  Freeport  (E). 

Lower 

Free- 

port 

(D). 

Upper  Kittanning  (C'). 

1. 

2. 

3. 

4. 

5.  ' 

6. 

4 

8. 

9. 

io: 

Sample  as  received: 

Moisture 

2.  65 

2.82 

3.  04 

4.73 

2.  81 

1. 67 

2.  60 

1.  94 

2.93 

3.  51 

Volatile  matter 

14.  86 

15.  61 

16.  27 

13.  78 

15. 07 

18.  52 

14. 10 

15.  81 

13.  47 

17.16 

Fixed  carbon 

72.  38 

70.32 

73.  47 

72.  27 

72.  64 

69. 14 

72.05 

70.  77 

74.06 

69.04 

Ash 

10.11 

11.  25 

7.22 

9.  22 

9.  48 

10.67 

11.  25 

11.  48 

9.  54 

10.29 

Sulphur 

2.06 

2.42 

2. 18 

1.  09 

1.  92 

3.  46 

2.79 

3.73 

1.  88 

2.  01 

Loss  of  moisture  on  air  drying. . 

2.  00 

2. 10 

2.  50 

4.00 

2.  20 

1.  00 

2.  00 

1.20 

2.20 

2.  30 

Air-dried  sample: 

Moisture 

.66 

.74 

.55 

.76 

.62 

.68 

.61 

. 75 

. 75 

1. 24 

Volatile  matter 

15. 16 

15-94 

16.  69 

14.35 

15.  41 

18.  71 

14.  39 

16.00 

13.  77 

17.56 

Fixed  carbon 

73.  86 

71.  83 

75.35 

75.  28 

74.28 

69.  84 

73.52 

71.63 

75.  73 

70.  67 

Ash 

10.  32 

11.  49 

7.41 

9.  61 

9.  69 

10.  77 

11.  48 

11.62 

9.75 

10.  53 

Sulphur 

2. 10 

2.  47 

2.  24 

1. 14 

1.96 

3.  49 

2.  85 

3.  78 

1.  92 

2.06 

Lower  Kittanning  (B). 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

Sample  as  received: 

. ("Moisture 

2.70 

2.03 

2.  81 

1.78 

2.  21 

2.  24 

2.63 

2.79 

3. 12 

3.  07 

g 1 Volatile  matter 

15.  64 

14.47 

14.66 

15. 19 

14.32 

15.70 

17.85 

17.  76 

17.  89 

17.  64 

*-•  ) Fixed  carbon 

74.03 

75.  31 

75.75 

73.  25 

78. 16 

78.  37 

73. 24 

73.  20 

70.85 

72.  85 

^ [(Ash 

7.  63 

8. 19 

6.78 

9.78 

5. 31 

3.69 

6.28 

6.25 

8. 14 

6.  44 

f\  Sulphur 

1.93 

2.  26 

1.33 

4.50 

.47 

.77 

1.  49 

1.88 

2.  74 

1.38 

. Hydrogen 

4. 14 

4. 16 

^ < Carbon 

79.97 

77. 10 

^ Nitrogen 

1.  26 

1.  41 

[Oxygen . . . 

4. 18 

3.05 

Calorific  value  determined: 

Calories 

7,823 

7,612 

British  thermal  units 

14,081 

13, 702 



Loss  of  moisture  on  air  drying. . 

1.80 

1.  40 

1.90 

1. 10 

1.60 

1.60 

2.00 

2. 10 

2.50 

2.50 

a All  analyses  given  in  this  paper,  unless  otherwise  stated,  were  made  at  the  fuel-testing  plant  of  the 
United  States  Geological  Survey  at  St.  Louis,  Mo.;  J.  A.  Holmes  in  charge;  F.  M.  Stanton,  chemist. 


COAL, 


41 


Analyses  of  coal  samples  from  Johnstown  quadrangle , Pennsylvania — Continued. 


Lower  Kittanning  (B)— Continued. 


11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

20. 

Air-dried  sample: 

f Moisture ...  . 

0.  91 

0.64 

0.93 

0.69 

0.  62 

0.65 

0.64 

0.  71 

0.64 

0.58 

Volatile  matter 

15.  93 

14.  67 

14.  94 

15.  36 

14.  55 

15.95 

18.21 

18. 14 

18.  35 

18.09 

»h  I Fixed  carbon 

75.  39 

76.  38 

77.22 

74.  06 

79.43 

79.  65 

74.  74 

74.  77 

72.  67 

74.  72 

^ (./Ash. 

7.  77 

8.  31 

6.  91 

9.  89 

5.  40 

3.  75 

6.  41 

6.  38 

8.34 

6.  61 

HSulphur 

1.  97 

2.29 

1.  36 

4.  55 

.48 

.78 

1.52 

1.92 

2.  81 

1.  42 

. (Hydrogen 

4.  04 

4.08 

S J Carbon 

81. 10 

77.95 

(Nitrogen 

1.  27 

1.  43 

[Oxygen 

2.  99 

2. 10 

Calorific  value  determined: 
Calories 

7,934 

14,281 

7,697 

13,854 

British  thermal  units 

! 

Lower  Kittanning  (B)— Continued. 


21. 

22. 

23. 

24. 

25. 

26, 

27. 

28. 

Sample  as  received: 

f Moisture 

2. 80 

3.45 

2.59 

3. 83 

2.  84 

3.13 

2.57 

3.49 

* 1 Volatile  matter 

17.30 

18. 82 

18.91 

19.  03 

17.47 

17.61 

18. 09 

16.12 

1 Fixed  carbon 

73.28 

71. 18 

70.  33 

67.89 

71.42 

69.  45 

69.  01 

74.68 

^ [/Ash 

6. 62 

6.  55 

8. 17 

9.  25 

8.27 

9.  81 

10.  33 

5.71 

n Sulphur 

2. 46 

2.  01 

4.04 

4. 57 

3.11 

3.  77 

3.97 

.95 

. Hydrogen 

4.  62 

4.43 

J Carbon 

76.41 

75.  89 

P Nitrogen. . 

1. 14 

1. 16 

[Oxygen 

4.25 

4.22 

Calorific  value  determined— 
Calories 

7,821 

14,079 

7, 664 
13,795 

7,618 

British  thermal  units . 

13,712 

Loss  of  moisture  on  air  drying 

2.  00 

3.00 

2.00 

3.30 

2. 40 

2. 80 

2. 10 

2. 80 

Air-dried  sample: 

. ("Moisture 

.82 

.46 

.60 

.55 

.45 

.34 

.48 

.71 

g 1 Volatile  matter 

17.65 

19.  40 

19.  30 

19.68 

17.  90 

18. 12 

18.48 

16.58 

s-d  Fixed  carbon 

74.  77 

73.38 

71.77 

70.  20 

73. 18 

71.45 

70.  49 

76. 83 

^ [/Ash 

6.  76 

6.  76 

8.33 

9.  57 

8.  47 

10. 09 

10.  55 

5. 88 

(/Sulphur 

.Hydrogen. 

2.  51 

2. 07 

4.12 

4.  73 

3.19 

3.88 
4.  43 

4.  06 
4.  29 

.98 

^ < Carbon 

78.61 

77.52 

^ Nitrogen 

1. 17 

1.18 

[Oxvgen. 

1.82 

2.  40 

Calorific  value  determined— 
Calories 

8,013 

7,885 
14, 193 

7, 781 

British  thermal  units 

14,423 

14, 006 

Lower  Kittanning  (B)— Continued. 


jBrook- 
I ville. 
(A). 


Sample  as  received: 

(Moisture , . . . 

Volatile  matter 

Fixed  carbon 

(Ash 

1\Sulphur 

Hydrogen 

Cafbon 

Nitrogen 

Oxygen 

Calorific  value  determined— 

Calories 

British  thermal  units 


29. 


3.09 
16. 66 
74.79 
5.46 
1.18 


30. 


2. 31 
13.  99 
76.  69 
7.01 
1.19 


31. 


1.10 
15. 80 
75.  69 
7.41 
1.49 


32. 


0.59 
16.  61 
76.  76 
6.  04 
.91 


2.20  1.60  2.30  2.00  3.60 


2. 80 
17.  92 
71.32 
7.  96 
2.  29 


2. 48 
17.  87 
70. 41 
9.  24 
3.03 


7,679 
13, 822 


4.00 
15.89 
69.  57 
10.  54 
2. 85 


7,415 

13,347 


36. 


2. 35 
14. 30 
71.40 
11.95 
3. 30 
4.22 
75. 16 
1.13 
4. 24 

7,382 

13,288 

1.80 


Loss  of  moisture  on  air  drying, 


42  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Analyses  of  coal  samples  from  Johnstown  quadrangle , Pennsylvania — Continued. 


Lower  Kittanning  (B)— Continued. 

Brook- 

ville. 

(A). 

30. 

31. 

32. 

33. 

34. 

35. 

36. 

Air-dried  sample: 

. f Moisture 

0.  91 
17.03 
76. 47 
5.  59 
1.21 

0. 72 
14.  22 
77.94 
7.12 
1.21 

0. 51 
18. 34 
73.00 
8.15 
2. 34 

0.  49 
18.23 
71.85 
9.  43 
3. 09 

0. 42 
16. 48 
72.17 
10.93 
2. 96 

0. 56 
14.56 
72.71 
12. 17 
3.36 
4.09 
76.53 
1.15 
2.71 

7,517 

13,532 

g 1 Volatile  matter 

1 Fixed  carbon 

^ (/Ash 

f\  Sulphur 

. Hvdrogen 

Carbon 

^ Nitrogen 

(.Oxygen  * 

Calorific  value  determined— 

Calories 

7.836 
14, 105 

7,692 

13,846 

British  thermal  units 

1 

1.  Conemaugh  slope. 

2.  Johnstown. 

3.  South  Fork. 

4.  Stony  Creek,  near  trolley  bridge  between  Mox- 

hom  and  Ferndale,  south  of  Johnstown. 

5.  South  Fork. 

6.  Franklin. 

7.  Dale. 

8.  Johnstown. 

9.  Moxhom. 

19.  Solomons  Run,  southeast  of  Johnstown. 

11.  Franklin. 

12.  Johnstown. 

13.  Near  Walsall. 

14.  Stony  Creek,  Somerset  County,  south  of  quad- 

rangle. 

15.  16.  South  Fork. 

17,  18.  Nanty  Glo. 

19.  Vintondale. 

20.  Twin  Rocks. 

21.  Near  Weber  Station,  Blacklick  Creek. 

22.  Twin  Rocks. 


23.  Wehrum. 

24,  25.  Wehrum.  Mine  samples;  see  Bull.  U.  S. 

Geol.  Survey  No.  332,  1908,  p.  201. 

26,  27.  Wehrum.  Car  samples;  see  Bull.  U.  S. 

Geol.  Survey  No.  332,  1908,  p.  201. 

28,  29.  Ehrenfeld.  J.  S.  Burrows,  collector;  see  Bull. 
U.  S.  Geol.  Survey  No.  290,  1906,  p.  179. 

30.  Scalp  Level. 

31,  32.  Windber.  Carload  shipped  by  operators 

from  Eureka  No.  31  mine  to  St'  Louis;  see 
Bull.  U.  S.  Geol.  Survey  No.  261,  1905,  p.  51. 
Eureka  No.  31  mine  is  not  in  the  Johnstown 
quadrangle,  and  the  correlation  of  the  coal 
bed  where  the  sample  was  procured  is  left 
open. 

33,  34.  Near  Conemaugh  Furnace.  Mine  samples; 
see  Bull.  U.  S.  Geol.  Survey  No.  332,  1908, 

p.  216. 

35.  Near  Conemaugh  Furnace.  Car  samples;  see 

Bull.  U.  S.  Geol.  Survey  No.  332,  1908,  p.  216. 

36.  South  Fork. 


DESCRIPTION  BY  DISTRICTS. 

For  convenience  in  reference  and  from  the  commercial  point  of 
view  the  coal  resources  of  the  Johnstown  quadrangle  are  described 
by  districts,  as  follows:  Johnstown  district,  South  Fork-Mineral 
Point  district,  Blacklick  Creek  district,  Windber  district,  and  Cone- 
maugh Furnace  district.  The  territory  included  in  these  different 
districts  will  be  outlined  in  the  descriptions. 

JOHNSTOWN  DISTRICT. 

EXTENT. 

The  Johnstown  district  includes  the  territory  about  the  city  of 
Johnstown  and  its  suburbs;  the  hills  along  the  valley  of  Conemaugh 
River,  extending  from  East  Conemaugh  and  Clapboard  Run  on  the 
east  to  Laurel  Run  and  the  base  of  Laurel  Ridge  on  the  west;  the 
region  along  Stony  Creek  and  its  tributaries,  Solomons  Run,  Sams 
Run,  and  Bens  Creek;  and  a few  smaller  areas  back  in  the  country 
and  away  from  the  channels  of  transportation. 


JOHNSTOWN  DISTRICT. 


43 


CONEMAUGH  COALS. 

CHARACTER  AND  DISTRIBUTION. 

The  Conemaugh  formation  outcrops  in  all  the  hills  in  the  immediate 
vicinity  of  Johnstown.  In  a section  of  300  feet  of  this  formation 
measured  by  John  Fulton®  above  the  Upper  Freeport  coal  at  Pros- 
sers Knob,  near  the  city,  but  3 inches  of  coal  was  detected  about  65 
feet  above  the  Upper  Freeport  coal.  A section  was  measured  on 
the  hill  above  the  plant  of  the  Johnstown  Pressed  Brick  Company 
in  which  400  feet  of  beds  with  concealed  intervals  were  observed 
(see  pp.  115-116),  and  no  bed  of  coal  was  detected  or  reported  as  of 
workable  thickness.  It  is  probable,  therefore,  that  in  the  Johnstown 
district  the  Conemaugh  formation  contains  no  bed  of  coal  which 
under  present  conditions  is  of  commercial  importance. 

GALLITZIN  COAL. 

In  the  vicinity  of  Johnstown  the  Gallitzin  coal  averages  about  100 
feet  above  the  Upper  Freeport  coal.  Some  of  the  diamond-drill  records 
obtained  in  the  hills  east  of  the  city  note  a coal  1 foot  in  thickness 
slightly  more  than  100  feet  above  the  Upper  Freeport.  The  maxi- 
mum thickness  of  this  bed  appears  to  be  less  than  2 feet  and  it  is  in 
places  less  than  1 foot  thick.  In  some  of  the  sections  a coal  appears 
as  low  as  70  feet  above  the  Upper  Freeport.  Where  there  is  but  a 
single  coal  in  the  lower  110  feet  of  the  Conemaugh  it  is  difficult  to 
decide  whether  it  is  the  representative  of  the  Gallitzin  or  of  the 
next  lower  bed,  the  Mahoning  coal.  What  is  believed  to  be  the 
equivalent  of  the  Gallitzin  has  been  noted  well  up  on  South  Fork  of 
Bens  Creek,  also  on  the  west  side  of  the  hill  south  of  Kring  and  west 
of  Ingleside,  and  there  is  evidence  that  it  has  been  prospected  in  both 
these  localities.  Its  position  was  located  on  the  Johnstown-Geistown 
road,  along  the  trolley  line  south  of  Island  Park.  Where  measured 
along  the  roadside  it  is  very  thin.  It  may  be  said  that  its  occurrence 
in  the  Johnstown  Basin  is  fairly  widespread  but  that  it  is  too  thin 
to  be  classed  among  the  future  workable  beds  in  this  part  of  the 
quadrangle. 

MAHONING  COAL. 

The  Mahoning  coal  occurs  very  close  to  and  above  the  Johnstown 
ore  bed  and  between  50  and  55  feet  above  the  Upper  Freeport  coal 
in  the  region  near  Johnstown.  It  consists  where  seen  to  best  advan- 
tage of  two  benches,  as  shown  in  the  following  section  measured 
above  the  Baltimore  and  Ohio  Railroad  tunnel  on  Stony  Creek  south 
of  Johnstown: 


a See  pp.  17-18,  this  bulletin;  also  Second  Geol.  Survey  Pennsylvania,  vol.  H2,  1877,  p.  97. 


44  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Section  of  Mahoning  coal  south  of  Johnstown. 


Shale  roof.  Ft.  in. 

Coal 5 

Shale,  drab,  fossiliferous 2 0 

Coal 6 

Fire  clay,  dark. 


It  is  nowhere  worked,  so  far  as  known,  and  it  can  not  be  considered 
among  the  future  workable  coals  of  the  area. 

ALLEGHENY  COALS. 


GEOLOGIC  POSITION. 

Four  coals  of  workable  thickness  occur  in  the  Allegheny  formation 
in  the  Johnstown  district — the  Upper  Freeport  or  Coke  Yard  bed, 
the  Lower  Freeport  or  Limestone  bed,  the  Upper  Kittanning  or 
Cement  bed,  and  the  Lower  Kittanning  or  Miller  bed.  These  are 
also  known  by  letters  as  the  E,  D,  C',  and  B coals,  respectively. 
The  Middle  Kittanning  also  occurs,  but  so  far  as  known  is  of  work- 
able thickness  at  only  a few  points  and  therefore  can  not  be  classed 
among  the  commercial  coals  of  the  district.  All  the  coals  except 
the  Lower  Kittanning  lie  at  convenient  intervals  above  drainage 
level  in  the  hills  immediately  surrounding  Johnstown  and  are  exten- 
sively worked. 

The  entire  Allegheny  formation  is  exposed  in  the  Johnstown  dis- 
trict. Several  sections  obtained  at  widely  scattered  points  serve  well 
to  illustrate  the  variations  in  the  character  of  its  rocks  as  well  as  the 
intervals  which  separate  the  coals.  The  sections  were  measured  by 
hand  leveling  and  by  rule.  Some  of  them  are  as  follows: 


(1)  Section  of  upper  part  of  Allegheny  formation  near  Valley  Coal  and  Stone  Company's 

mine , on  Stony  Creek. 


Ft.  in. 


Coal,  Upper  Freeport  (E  or  Coke  Yard  coal) 3 3 

Shale 14 

Shales,  dark,  concretionary 10 

Shales,  blue 25 

Sandstone,  laminated 5 


Shales  and  sandy  shales.. 

Coal,  1 foot ‘ 

Bone,  1^  inches 

Coal,  1 foot  7 inches 

Bone,  1 inch 

Coal,  3^  inches 

Limestone 

Shale  and  sandstone 

Shale,  blue 15 


Lower  Freeport  (D  or  Limestone! 
coal).  / 


3 1 


Coal,  Upper  Kittanning  (Cement  or  C'  coal) 

Shale 

Limestone 

Shale,  sandy,  containing  limestone  concretions . 
Sandstone,  massive. 


4 9 

to  5 5 

1 

3F4 

8-10 


JOHNSTOWN  DISTRICT. 


45 


The  interval  between  the  Upper  Freeport  and  Upper  Kittanning 
coals  in  the  above  section  is  about  90  feet. 

The  section  is  carried  still  lower  by  one  measured  south  of  the 
tunnel  on  the  Baltimore  and  Ohio  Railroad,  which  shows  the  relative 
positions  of  two  small  beds  occurring  between  the  Upper  Kittanning 
or  Cement  bed  and  the  Lower  Kittanning  or  Miller  bed.  This  section 
is  as  follows: 


(2)  Section  of  Upper  Kittanning  coal  and  underlying  coals  south  of  tunnel  on  Baltimore 

and  Ohio  Railroad. 


Ft.  in. 

Coal,  Upper  Kittanning  (Cement  or  O'  bed) 5 2 

Shale 8-12 

Limestone 6 

Shales,  gray,  concretionary 4-5 

Shale,  drab,  containing  abundant  ferruginous  limestone  con- 
cretions   6 

Shale,  black 12-14 

Coal 1^ 

Shale,  blue,  with  ferruginous  limestone  concretions 6 

Shale,  sandy 6 10 

Coal 

The  intervals  between  the  three  main  coals  in  the  upper  part  of 


the  Allegheny  formation,  as  well  as  the  character  of  the  intermediate 
rocks,  are  given  in  the  following  section  obtained  in  the  ventilating 
shaft  of  the  Rolling  Mill  mine  of  the  Cambria  Steel  Company  on  Mill 
Creek: 


(3)  Section  of  upper  part  of  Allegheny  formation  on  Mill  Creek. 


Upper  Freeport  coal.  Feet. 

Concealed 20 

Concealed  by  mine  timber 22 

Shale,  hard 6 

Sandstone 4 

Shale 3J 

Coal,  Lower  Freeport  (Limestone  or  D coal) 1J 

Limestone,  nodular 2 

Shale,  dense,  drab,  or  clay 10 

Shale,  blue,  irregularly  bedded 4 

Shale,  light  drab 7 

Sandstone 3 

Shale 3 

Shale,  sandy 8 

Top  of  Cement  coal. 


The  interval  between  the  Upper  Freeport  and  Upper  Kittanning 
coals  here  is  between  90  and  95  feet. 

The  following  section  was  measured  by  F.  B.  Peck  and  W,  C. 
Phalen  on  the  Eighth  Ward  road,  south  of  Kernville: 


46  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

(4)  Section  of  upper  part  of  Allegheny  formation  on  Eighth  Ward  road,  south  of  Kernville. 

Ft.  in. 

Coal,  3 feet  8 inchesl  Main  Upper  Freeport  (Coke  yard  or  El  , , 

Clay,  4 inches coal).  f 4 d 

Coal,  3 inches J 

Clay 2 6 

Coal 3 

Shale 5 

Shales,  ferruginous 10 

Sandstone,  argillapeous 8 

Sandstone,  concretionary 3 

Sandstone,  massive 19 


Lower  Freeport  (Limestone  or  D bed)  4 1 


Shale,  black 

Sandstone 

Shale,  black 

Coal,  7-8  inches.. 

Bone,  §-l  inch 

Coal,  8 inches 

Shale,  black,  2 inches 
Coal,  2 feet  6 inches. 

Shale,  black 

Limestone 3 

Shale,  blue 5 

Shale,  massive,  drab,  ferruginous 7 

Shale,  sandy 8 

Shale,  blue-black 4 

Coal,  Upper  Kittanning  (Cement  or  O'  bed) 3 

Shale 1 

Limestone 5 

Shale 3 

Shale,  sandy 5 

Shale,  black  and  brown 3 

Coal 1 

Shales,  sandy 5 

Shales 20 

Coal ' 

Shales 25 


11 


The  interval  here  between  the  Upper  Freeport  and  the  Upper  Kit- 
tanning coals  is  about  85  feet. 

The  following  section  is  of  interest,  as  it  shows  a coal  between  the 
Lower  Freeport  and  Upper  Kittanning  beds,  presumably  the  same 
bed  as  that  above  the  Upper  Kittanning  at  the  mouth  of  the  Rolling 
Mill  mine  and  on  Dalton  Run. 


(5)  Section  of  upper  part  of  Allegheny  formation  south  of  stone  bridge  on  Stony  Creek, 

Johnstown. 

Coal,  6 inches 


Bone,  1 inch 

Coal,  inches 

Shale,  1 inch 

Coal,  1 foot  7 inches 

Fire  clay 

Shale 


Lower  Freeport  (Limestone  or  D1 
coal) J 


Ft.  in. 

2 9£ 

1 

3 


JOHNSTOWN  DISTRICT. 


47 


Ft.  in. 

Limestone 2 6 

Shales 17-18 

Coal 8 

Bone 9 

Shales,  brown,  with  concretions 3 6 

Shale,  sandy 8 4 

Top  of  cement  coal. 


The  following  section  was  measured  in  a small  gully  on  the  main 
line  of  the  Pennsylvania  Railroad  half  a mile  east  of  Conemaugh 
depot. 


(6)  Section  of  upper  part  of  Allegheny  formation  on  Pennsylvania  Railroad  east  of  East 

Conemaugh. 

Ft.  in. 


Coal,  3 feet  3 inches'! 

Bone,  2 inches >Upper  Freeport  (Coke  Yard  or  E coal).  3 

Coal,  A.\  inches J 

Shales 18 

Shale  and  sandstone  beds 12 

Shales 4 10 

Coal 8 

Fire  clay 4 

Limestone,  green  sandy 6 

Sandstone,  laminated 6 

Sandstone,  shaly 5 

Sandstone,  massive 40 

Coal,  Upper  Kittanning  (Cement  or  C'  coal) 2 11J 

Limestone 2 

Shale,  gray,  with  limestone  nodules 1 6 

Limestone ’ ....^ 5 

Shale,  gray,  with  ferruginous  concretions 5 

Shales,  blue 17 

Railroad  level. 

Shale,  blue,  with  ferruginous  limestone  concretions 10 

Limestone  nodules,  blue,  to  creek  level. 


The  above  section  was  completed  down  to  the  Lower  Kittanning 
coal  by  a section  a short  distance  to  the  west.  Part  of  it  could  not 
be  hand  leveled  but  had  to  be  measured  by  barometer.  The  section 
is  as  follows: 


(7)  Section  between  Upper  Kittanning  (C')  and  Lower  Kittanning  (B)  coals. 

Base  of  Upper  Kittanning  (C7  or  Cement  coal). 

Shales,  bluish  and  gray  (containing  a small  coal  locally),  with 
concretions;  40  feet  of  these  shales  are  represented  in  the  pre-  Ft.  in. 


ceding  section 50 

Coal 10i 

Shales,  greenish  blue 6 8 

Sandstone,  gray 1 9 

Shale,  black 1 5 

Sandstone,  blue,  thick  bedded 5 8 


Approximate  interval  made  up  chiefly  of  sandstone  to  Lower 
Kittanning  (Miller  or  B bed) 


25± 


48  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


The  above  sections  well  illustrate  the  character  of  the  Allegheny 
rocks  between  the  Lower  Kittanning  (Miller)  coal  and  the  Upper 
Freeport  (Coke  Yard)  bed.  The  opportunities  for  measuring  the 
interval  from  the  Lower  Kittanning  to  the  top  of  the  Pottsville  are 
rare  near  Johnstown.  On  Clapboard  Kun  this  interval  is  about  70 
feet.  On  Stony  Creek  south  of  the  area  the  character  of  the  rocks 
making  up  the  interval  was  carefully  determined  and  the  section 
hand  leveled.  This  section  of  the  lower  Allegheny  is  as  follows: 

(8)  Section  from  top  of  Pottsville  to  Lower  Kittanning  ( Miller  or  B coal)  on  Stony  CreeJc, 
south  of  Johnstown  quadrangle. 


Coal,  3 feet  inches ' 

Bone  or  black  shale,  inches 

Coal,  3§  inches 

Bone,  1 inch 

Coal,  10  inches 

Fire  clay 

Sandstone,  gray,  laminated 

Sandstone,  massive 

Shale 

Coal  and  bone 

Shale 

Sandstone,  laminated 

Top  of  Pottsville. 


Lower  Kittanning  (Miller  or' 
B coal) 


Ft. 

5 


4 
9 

40 

2 

3 

10 

5 


8 

8 

7 


The  interval  from  the  base  of  the  Lower  Kittanning  coal  to  the  top 
of  the  Pottsville  here  is  about  75  feet,  which  is  very  close  to  the 
interval  of  70  feet  measured  on  Clapboard  Run. 

In  this  section  but  one  coal  appears  between  the  top  of  the  Potts- 
ville and  the  base  of  the  Lower  Kittanning  (Miller)  bed,  but  in  places 
two  coals  occur  in  this  interval,  as  in  the  section  of  the  lower  Alle- 
gheny rocks  obtained  near  the  brick  plant  of  A.  J.  Haws  & Sons 
(Limited),  west  of  Coopersdale.  (See  p.  24,  fig.  2,  section  A.) 

Many  other  measurements  of  the  intervals  between  the  coals  of 
the  Allegheny  were  obtained  in  and  near  Johnstown.  (See  fig.  2.) 
These  intervals  and  those  brought  out  in  the  sections  given  above 
will  be  described  in  detail  in  considering  the  stratigraphy  of  the  indi- 
vidual coal  beds. 


UPPER  FREEPORT  COAL. 


Name  and  position. — In  the  Johnstown  district  the  Upper  Freeport 
or  top  coal  of  the  Allegheny  formation  is  commonly  known  as  the 
Coke  Yard  coal,  from  the  fact  that  it  was  coked  in  the  early  days  of 
the  iron  industry  at  the  old  Cambria  furnace  on  Laurel  Run.  It  is 
also  frequently  referred  to  as  the  E coal.  It  lies  at  the  top,  indeed 
marks  the  top,  of  the  Allegheny  formation,  being  separated  from  the 
usually  massive  Mahoning  sandstone  member  (of  the  Conemaugh  for- 
mation) above  by  a few  feet  of  shales,  and  being  located  between  255 
and  265  feet  above  the  top  of  the  Pottsville  formation,  or  1 ‘Conglomer- 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  447  PLATE  VII 


A.  EXPOSURE  OF  UPPER  KITTANNING  COAL  AND  JOHNSTOWN  LIMESTONE  MEMBER 
("CEMENT  BED"  IN  THE  ILLUSTRATION)  ON  STONY  CREEK,  NEAR  MINE  OF  VALLEY 
COAL  AND  STONE  COMPANY. 


B.  UPPER  FREEPORT  COAL  WITH  OVERLYING  SHALES  AND  BASE  OF  MAHONING  SANDSTONE 
AT  SOUTH  PORTAL  OF  BALTIMORE  AND  OHIO  RAILROAD  TUNNEL,  STONY  CREEK. 


JOHNSTOWN  DISTRICT. 


49 


ate  Rock,”  as  it  is  popularly  known.  Its  relation  to  the  other  coals 
in  the  Allegheny  formation  are  shown  in  figure  2 and  may  be  learned 
from  most  of  the  sections  just  given  (pp.  44-47). 

Extent  and  development. — The  Upper  Freeport  is  present  in  all  the 
hills  along  Conemaugh  River  near  the  city  and  its  suburbs,  extending 
as  far  to  the  west  as  the  hills  bordering  east  of  Laurel  Run.  It  is  also 
above  drainage  level  on  Clapboard,  Hinckston,  and  St.  Clair  runs  and 
practically  along  the  entire  course  of  Stony  Creek  and  its  tributaries, 
Solomons  and  Sams  runs.  It  is  not  above  drainage  level  through  the 
entire  course  of  Bens  Creek  in  this  area,  as  the  synclinal  trough  in 
Somerset  County  causes  its  disappearance  for  a short  distance,  but 
even  there  it  is  not  deeply  buried.  Plate  I gives  an  excellent  idea  of 
its  outcrop  in  the  vicinity  of  Johnstown. 

Wherever  the  coal  is  exposed  it  has  been  worked  fairly  extensively, 
and  it  is  now  being  worked  on  a large  scale  in  many  mines  about 
Johnstown.  The  most  important  workings  are  those  of  the  Cambria 
Steel  Company  at  the  Conemaugh  slope.  The  Ferndale  Coal  Com- 
pany also  operates  on  an  extensive  scale.  Many  smaller  mines  on 
this  coal  bed  are  worked  the  year  round,  and  many  small  banks,  from 
which  coal  is  never  shipped  by  rail,  are  worked  only  during  the  winter 
season.  The  most  important  mines  on  this  coal  are  indicated  on 
Plate  I. 

Chemical  character. — The  composition  of  the  Upper  Freeport  coal 
in  the  Johnstown  district  is  shown  in  analyses  1 and  2,  on  page  40. 
These  analyses  indicate  this  coal  to  be  a high-carbon  coal  with  com- 
paratively low  moisture.  The  ash  and  the  sulphur  are  high. 

Occurrence  and  physical  character. — Average  and  typical  sections  of 
the  Upper  Freeport  coal  in  the  Johnstown  district  are  shown  in  figure 
4.  The  main  bench  averages  between  3 feet  and  3 feet  10  inches  in 
thickness,  more  nearly  the  former  than  the  latter.  In  places  there 
is  present  a lower  bench,  which  only  exceptionally  (as  at  the  mine  of 
Lewis  Eppley,  on  Hinckston  Run)  exceeds  4 or  5 inches  in  thickness. 
This  lower  bench  is  separated  from  the  main  bench  by  a thin  bone 
or  shale  parting  rarely  more  than  5 or  6 inches  thick.  The  lower 
part  of  the  coal  bed  is  in  some  places  so  intimate  a mixture  of  coal 
and  bone  that  it  is  difficult  to  differentiate  the  two.  Such  is  the  case 
in  section  19,  obtained  at  the  south  portal  of  the  tunnel  of  the  Balti- 
more and  Ohio  Railroad  on  Stony  Creek.  (See  PI.  VII,  B.)  At  a 
bank  on  Bens  Creek  the  coal  shows  a section  (No.  21)  quite  different 
from  the  usual  one,  but  this  section  was  obtained  at  a point  several 
miles  away  from  most  of  the  other  sections,  and  the  lack  of  measure- 
ments in  the  intermediate  territory  makes  it  impossible  to  state 
whether  the  thinning  shown  is  local  or  general  to  the  west  of  the 
Johnstown  Basin.  However,  to  the  north  of  this  point,  on  St.  Clair 
69516°— Bull.  447—11 4 


50  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Run,  the  section  seems  to  be  as  usual.  Only  the  main  bench  of  this 
coal  is  ever  worked,  and  all  the  coal  below  the  main  bench  serves  as  a 
floor,  except  where  it  is  necessary  to  remove  it  for  head  room. 

As  a rule  no  partings  were  noted  in  the  main  bench  of  this  coal  in 
the  Johnstown  district,  a particular  in  which  it  differs  markedly  from 
the  equivalent  bed  about  South  Fork  and  along  the  southeastern 
flank  of  the  Wilmore  Basin.  Its  maximum  thickness  nowhere  exceeds 
5 feet  and  usually  ranges  near  4 feet.  The  minimum  thickness  may 


Figure  4.— Sections  of  the  Upper  Freeport  (E  or  Coke  Yard)  coal  in  the  Johnstown  district. 

Scale,  1 inch=5feet. 


1.  Lewis  Eppley,  Hinckston  Run,  above  Rosedale. 

2.  Conemaugh  slope,  Cambria  Steel  Company,  west  of  East  Conemaugh. 

3.  Country  bank  in  ravine,  north  of  Pennsylvania  Railroad,  northeast  of  East  Conemaugh. 

4.  L.  J.  Mitchell,  mouth  of  Clapboard  Run. 

5.  Charles  Umbarger,  head  of  Clapboard  Run. 

6.  Johnstown  Pressed  Brick  Company,  Frankstown  road. 

7.  William  Davis,  Frankstown  road. 

8.  William  Schaeffer,  Shingle  Run,  Dale. 

9, 10, 11, 12.  Berkebile  Coal  Company,  Dale,  north  of  Moxhom. 

13.  Country  bank,  Sams  Run,  just  above  Highland  Coal  and  Coke  Company’s  mine. 

14.  Ferndale  Coal  Company,  Grubtown  opening 

15.  Ferndale  Coal  Company. 

16.  Country  bank,  Roxbury. 

17.  Natural  exposure  along  trolley  line,  opposite  Valley  Coal  and  Stone  Company’s  mine. 

18.  Natural  exposure  along  trolley  line,  south  of  Island  Park. 

19.  South  portal  of  Baltimore  and  Ohio  Railroad  tunnel,  south  of  Johnstown. 

20.  Natural  exposure  on  Stony  Creek  near  mine  of  Valley  Coal  and  Stone  Company. 

21.  Bens  Creek,  Somerset  County. 

22.  Country  bank,  St.  Clair  Run. 


be  regarded  as  2 feet,  though,  as  in  all  coal  beds,  local  rolls  pinch  the 
coal  out  altogether.  Such  rolls,  however,  appear  to  be  extremely 
rare  in  this  coal  bed,  which  is  characterized  by  marked  uniformity. 
There  are  few  or  no  clay  veins.  The  roof  is  usually  shale  or  shaly 
sandstone,  in  places  bony.  It  is  generally  firm,  but  draw  slate  is 
occasionally  reported.  In  some  of  the  mines  great  care  is  taken  in 
propping  to  prevent  falls. 


JOHNSTOWN  DISTRICT. 


51 


LOWER  FREEPORT  COAL. 

Name  and  'position. — The  next  lower  coal  of  importance  in  the 
Allegheny  formation  in  the  Johnstown  district  is  the  Lower  Freeport 
or  D coal.  It  is  popularly  known  as  the  Limestone  coal,  and  is  better 
known  about  Johnstown  under  this  name  than  under  either  of  the 
other  two. 

It  lies  from  50  to  65  feet  below  the  Upper  Freeport  (Coke  Yard) 
coal  and  from  25  to  36  feet  above  the  Upper  Kittanning  (Cement) 
coal  in  the  valley  of  Stony  Creek,  both  south  and  west  of  Johnstown. 
On  Mill  Creek  it  is  55  feet  below  the  Upper  Freeport  coal  and  about  37 
feet  above  the  Upper  Kittanning  coal.  On  Peggys  Run,  near  the 
Franklin  mine  of  the  Cambria  Steel  Company,  it  is  58  feet  below  the 
Upper  Freeport  and  45  feet  above  the  Upper  Kittanning,  which  is 
here  worked.  In  section  6,  page  47,  the  8-inch  coal  35  feet  below  the 
Upper  Freeport  coal  may  not  be  the  representative  of  the  Lower 
Freeport;  certainly  its  distance  below  the  Upper  Freeport  is  very 
much  less  than  that  usual  in  the  district  as  a whole. 

Extent  and  development. — The  Lower  Freeport  coal  is  above  drain- 
age level,  as  is  the  Upper  Freeport  bed,  in  all  the  hills  near  Johnstown, 
outcropping  along  Conemaugh  River,  Stony  Creek,  and  their  tribu- 
taries. Its  outcrop  line,  if  drawn  on  the  map  (PI.  I),  would  fall 
between  that  of  the  Upper  Freeport  and  Upper  Kittanning  coals. 

The  coal  has  been  prospected  at  many  points  about  the  city  and 
its  suburbs,  but  it  is  not  mined,  at  least  on  a commercial  scale,  at  the 
present  time.  The  most  promising  outcrops  were  observed  along 
Stony  Creek  from  the  vicinity  of  the  mines  of  the  Valley  Coal  and 
Stone  Company  northward  to  Roxbury.  On  Peggys  Run,  near 
Franklin,  it  was  prospected  and  proved  to  be  4 feet  thick  but  so 
badly  broken  by  partings  that  it  is  not  commercially  valuable.  It  is 
reported  18  inches  thick  with  a shale  band  in  the  middle  in  the  hills 
north  of  Coopersdale.  It  is  believed  to  be  one  of  the  important 
coals  of  the  future  in  this  district,  especially  along  Stony  Creek. 

Chemical  character. — In  the  sample  of  coal  collected  south  of  Johns- 
town, the  analysis  of  which  is  given  on  page  40  (No.  4),  the  clay  part- 
ings were  not  included,  as  these  will  be  discarded  when  the  coal  is 
worked  on  a commercial  scale. 

In  the  analysis  the  percentage  of  carbon  is  high  and  comparable 
with  this  constituent  in  other  coals  in  this  district.  The  moisture 
can  not  be  considered  representative,  as  the  sample  was  procured 
near  the  outcrop.  The  ash  runs  rather  high  but  not  above  the 
average  of  the  coals  of  the  area.  The  coal  from  this  bed  is  not  con- 
sidered good  in  the  region  about  Johnstown,  but  the  analysis  of  the 
sample  collected  near  Stony  Creek  (see  p.  40)  indicates  that  in  this 
locality,  where  the  coal  is  persistent  and  of  workable  thickness,  it 
has  commercial  importance. 


52  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Occurrence  and  physical  character. — The  Lower  Freeport  coal 
occurs  as  a rule  in  three  distinct  benches  (see  fig.  5)  in  the  territory 
about  Johnstown  and  from  Ferndale  southward  on  Stony  Creek. 
These  benches  are  separated  by  thin  shale  or  bone  partings.  The 
top  bench  averages  about  a foot  in  thickness  and  the  middle  bench 
about  2 feet.  In  the  commercial  development  of  this  coal  bed  only 
these  two  benches  will  be  worked,  the  underlying  coal  and  bone 
serving  as  a floor.  It  may  be  said,  therefore,  that  in  this  locality 
there  is  present  from  2J  to  3 feet  of  coal.  Southeast  of  Johnstown, 
at  Dale  and  on  Sams  and  Solomons  runs,  where  this  coal  was  meas- 
ured by  F.  B.  Peck  and  Lawrence  Martin,  a thin  bench,  usually  under 
6 inches,  occurs  at  the  top  of  the  bed,  and  the  two  main  benches 
are  below,  separated  by  bone  or  shale.  In  this  part  of  the  district 
these  two  workable  benches  do  not  average  as  much  coal  as  in  the 
workable  parts  of  the  bed  on  Stony  Creek. 


Figure  5.— Sections  of  the  Lower  Freeport  (D  or  Limestone)  coal  in  the  Johnstown  district. 

Scale,  1 inch=5  feet. 

1.  Natural  exposure  south  of  Kernville,  near  Qitizens  Eighth  Ward  mine. 

2.  Exposure  on  Baltimore  and  Ohio  Railroad,  west  bank  of  Stony  Creek,  opposite  Lorraine  Steel  Com- 
pany’s plant. 

3.  Stony  Creek  near  trolley  bridge. 

4.  Stony  Creek  near  Valley  Coal  and  Stone  Company’s  mine. 

5.  West  bank  of  Stony  Creek,  Johnstown. 

6.  Sams  Run. 

7.  Dale. 

8.  9.  Head  of  Solomons  Run. 

Immediately  over  the  coal  are  usually  a few  inches  of  bone  and 
black  shale  overlain  by  dense  shale,  sandy  shale,  or  massive  sand- 
stone. Plate  IV,  A (p.  24),  gives  an  idea  of  the  character  of  this  roof. 
The  coal  is  underlain  by  clay,  below  which  occurs  the  limestone, 
though  in  places  the  limestone  underlies  the  coal  directly. 

UPPER  KITTANNING  COAL. 

Name  and  position. — The  next  lower  coal  of  importance  in  this  dis- 
trict is  the  Upper  Kittanning  coal.  It  is  also  referred  to  as  the  C' 
coal,  but  more  commonly  is  known  as  the  Cement  seam,  from  the 
bed  of  cement  rock  which  closely  underlies  it.  In  the  early  reports 
of  the  Second  Geological  Survey  of  Pennsylvania  it  was  called  the 
Lower  Freeport  or  D coal  and  the  coal  next  above  it  was  referred 
to  as  the  Middle  Freeport  or  D'  bed.® 


a Second  Geol.  Survey  Pennsylvania,  Rept.  112, 1877,  p.  xxviii. 


JOHNSTOWN  DISTRICT. 


53 


The  Upper  Kittanning  coal  commonly  occurs  within  100  feet  of 
the  Upper  Freeport  (Coke  Yard)  bed.  At  Kernville  the  interval  be- 
tween the  two  is  about  90  feet;  on  Stony  Creek  near  the  Valley  Coal 
and  Stone  Company’s  mine  it  is  90  feet;  on  Mill  Creek,  between  90 
and  95  feet;  south  of  Kernville,  on  the  trolley  line,  84  feet.  On  the 
Frankstown  road  an  interval  of  about  100  feet  was  measured,  though 
it  was  reported  that  the  two  coals  locally  occur  as  near  to  each  other 
as  80  feet.  Along  the  main  line  of  the  Pennsylvania  Railroad  just 
east  of  Conemaugh  depot  the  interval  is  90  feet,  and  near  the 
Franklin  mines  it  was  reported  as  103  feet.  It  can  be  stated,  there- 
fore, that  about  95  feet  below  the  Upper  Freeport  (Coke  Yard)  coal 
the  prospector  may  expect  to  find  the  representative  of  the  Upper 
Kittanning  (Cement)  coal  in  the  Johnstown  district.  Sections  1, 
3,  4,  and  6,  on  pages  44  to  47,  and  the  compiled  sections  obtained 
near  Coopersdale  and  on  Clapboard  and  Peggys  runs  (fig.  2)  clearly 
indicate  its  relation  to  all  the  coals  in  this  district. 

Extent  and  development. — The  Upper  Kittanning  (Cement)  seam 
outcrops  at  a height  above  drainage  level  that  is  convenient  for 
exploitation  at  practically  all  points  about  Johnstown.  West  of  the 
city  and  north  of  Conemaugh  River  the  coal  is  worked  on  the  estate 
of  Lewis  J.  Prosser,  at  the  north  end  of  Ten  Acre  Bridge.  Here  the 
coal  is  just  below  the  flood-plain  level  at  the  base  of  the  hill  and  has 
to  be  reached  by  slopes.  A short  distance  to  the  west,  just  back  of 
Coopersdale,  a slight  rise  in  the  beds  brings  this  coal  above  the  flood 
plain,  and  a few  abandoned  banks  indicate  that  it  was  formerly 
worked  on  a small  scale  here.  The  steep  rise  in  the  formations  toward 
the  west  does  not  allow  it  to  appear  in  the  hills  west  of  Laurel 
Run.  To  the  east  of  the  synclinal  axis  along  Hinckston  Run  the 
coal  is  above  drainage  level  and  was  worked  just  above  the  present 
location  of  Johnstown  depot.  Though  not  now  exposed  at  that 
exact  point,  the  fairly  massive  sandstone  which  usually  overlies  it 
is  well  exposed  near  the  position  of  the  old  Ray  furnace.  A very 
short  distance  to  the  east  the  coal  appears  in  the  cliffs  bordering  the 
railroad,  and  it  may  be  traced  beyond  Conemaugh  depot.  At  pres- 
ent there  are  no  workings  of  note  on  it  east  of  Johnstown  depot  and 
north  of  the  Little  Conemaugh,  though,  as  will  be  seen  from  section 
6,  page  47,  it  is  3 feet  thick  and  hence  workable  in  this  general 
locality. 

South  of  Conemaugh  River,  well  up  toward  the  head  of  Clapboard 
Run,  the  coal  is  worked  in  a small  way  at  the  present  time.  It  is 
2 feet  10  inches  thick  at  the  mine  of  Harry  Wissinger,  and  this  indi- 
cates that  its  thickness  south  of  the  river  is  much  the  same  as  that  to 
the  north,  near  Conemaugh  depot.  A few  old  openings  on  the  bed 
were  also  noticed  near  the  mouth  of  Clapboard  Run.  On  Peggys 
Run  is  located  Franklin  No.  1 mine  of  the  Cambria  Steel  Company. 
In  the  eastern  part  of  Johnstown,  on  the  Frankstown  road,  the  coal 


54  MINERAL  RESOURCES  OE  JOHNSTOWN,  PA.,  AND  VICINITY. 


is  opened  at  a few  mines,  the  workings  of  at  least  one  of  which  extend 
through  the  hill  and  come  out  on  the  Dale  road  leading  to  Walnut 
Grove.  In  Dale  the  coal  has  been  opened  by  numerous  private 
individuals  and  companies,  and  the  workings  extend  eastward  to 
Walnut  Grove  and  well  up  to  the  head  of  Solomons  Run.  The 
more  important  mines  and  banks  are  shown  on  Plate  I,  and  the  char- 
acter of  the  coal  bed  will  be  outlined  subsequently.  (See  pp.  54-56.) 
In  the  hill  between  Dale  and  Moxhom  and  on  Sams  Run  east  of 
Moxhom  the  coal  is  very  thick  (see  sections  11,  12,  and  13,  below) 
and  is  worked  by  the  Highland  Coal  and  Coke  Company  and  the 
Sunnyside  Coal  Company.  Farther  south,  on  Stony  Creek,  toward 
Kring,  this  coal  bed  thickens  from  3 or  4 feet  to  as  much  as  6 feet  in 
places,  as  near  the  mine  of  the  Valley  Coal  and  Stone  Company, 
though  that  company  mines  only  about  5 feet.  (See  PL  VII,  A.) 
In  the  cut  on  the  Baltimore  and  Ohio  Railroad  north  of  Kring  5 feet 
2 inches  of  coal  was  measured.  (See  section  2,  p.  45.)  This  thick 
coal  continues  southward.  The  westward  dips  toward  the  Johns- 
town Basin  carry  this  bed  below  drainage  level  less  than  a mile 
southeast  of  the  Baltimore  and  Ohio  Railroad  tunnel  south  of 
Moxhom. 

West  of  Stony  Creek  and  2 miles  southwest  of  Kring,  on  a creek 
unnamed  on  the  map,  the  Upper  Kittanning  (Cement)  coal  has  been 
opened  by  the  Kelso  Smokeless  Coal  Company.  Here  also  more 
than  5 feet  of  coal  was  measured.  Where  observed  along  Bens 
Creek  in  Somerset  County  the  bed  is  also  of  workable  thickness.  It 
has  been  opened  near  the  confluence  of  the  north  and  south  forks  of 
Bens  Creek,  on  the  land  of  Elizabeth  Cable,  on  Dalton  Run,  and  at 
the  reservoir  dam  on  Dalton  Run.  In  this  locality  the  small  seam 
overlying  the  Upper  Kittanning  was  observed.  In  the  region  north 
of  Bens  Creek  the  coal  is  4 feet  or  more  in  thickness.  Immediately 
West  of  Johnstown  the  operations  of  the  Cambria  Steel  Company 
have  been  pushed  westward  in  Upper  Yoder  Township  beyond  Mill 
Creek,  and  the  coal  has  shown  no  tendency  to  become  too  thin  to 
work.  The  Rolling  Mill  mine,  in  which  these  extensive  operations 
are  in  progress.,  is  the  largest  mine  in  the  area  and  indeed  one  of  the 
largest  in  the  State. 

In  the  hills  back  of  Cambria  the  Upper  Kittanning  (Cement)  bed 
is  above  drainage  level  and  has  been  opened  in  many  places.  At  the 
mines  of  Samuel  and  E.  W.  Fuge  the  coal  is  about  3 feet  in  thickness. 
In  the  hills  west  of  Morrellville  the  coal  has  been  mined  and  may  be 
assumed  to  be  of  workable  thickness.  It  may  be  stated,  therefore, 
that  all  about  Johnstown  the  Upper  Kittanning  coal  is  workable. 

Chemical  character. — Analyses  5 to  10,  page  40,  indicate  the  com- 
position of  this  coal. 

The  analyses  show  a high-carbon  coal  with  correspondingly  low 
volatile  matter.  The  moisture  is  low,  but  ash  and  sulphur  are  high. 


JOHNSTOWN  DISTRICT. 


55 


23 


Figure  6. — Sections  of  the  Upper  Kittanning  (C'  or  Cement)  coal  in  the  Johnstown  district. 
Scale,  1 inch  = 5 feet. 

1.  Cambria  Steel  Company,  Rolling  Mill  mine. 

2.  L.  Prosser,  north  end  Ten  Acre  Bridge. 

3.  E.  W.  Fuge,  Cambria. 

4.  Samuel  Fuge,  Cambria. 

5.  6.  In  cut  on  Baltimore  and  Ohio  Railroad,  west  side  of  Stony  Creek,  opposite  Moxhom. 

7.  In  cut  on  Baltimore  and  Ohio  Railroad  north  of  Kring. 

8.  Natural  exposure,  near  Valley  Coal  and  Stone  Company’s  mine. 

9.  Valley  Coal  and  Stone  Company. 

10.  Kelso  Smokeless  Coal  Company. 

11.  Highland  Coal  and  Coke  Company,  Sams  Run,  east  of  Moxhom. 

12, 13.  Sunnyside  Coal  Company,  between  Dale  and  Moxhom. 

14.  George  Heidingsfelder,  head  of  Solomons  Run. 

15.  D.  D.  Stoll,  head  of  Solomons  Run. 

16.  Jacoby  mine,  eastern  part  of  Dale  or  Walnut  Grove. 

17.  Wertz  & Miller,  Walnut  Grove. 

18.  William  Rohde,  Solomons  Run,  east  of  Dale. 

19.  Edward  Litsinger,  Solomons  Rim,  east  of  Dale. 

20.  Suppes  Coal  Company,  Chas.  H.  Suppes,  jr.,  Dale  opening. 

21.  22.  Citizens’  Coal  Company,  Dale  mine. 

23.  Caddy  mine. 

24.  Fyock’s  mine. 

25.  Jacoby  mine  (second  opening),  Dale. 

26.  Suppes  Coal  Company,  Chas.  H.  Suppes,  jr.,  Frankstown  road  opening  to  Dale  mine.  (See  No.  20.) 

27.  Natural  exposure,  east  of  Johnstown. 

28.  John  F.  Griffith,  Frankstown  road,  Johnstown. 

29.  Head  of  Clapboard  Run. 

30.  Cambria  Steel  Company,  Franklin  No.  1. 

31.  Dalton  Run,  at  the  reservoir. 

32.  Dalton  Run,  Elizabeth  Cable. 

33.  William  McAuliff,  Bens  Creek,  near  confluence  of  North  and  South  forks. 


56  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Occurrence  and  physical  character. — West  of  Johnstown,  at  the 
Cambria  openings  south  of  Conemaugh  River,  and  north  of  Cone- 
maugh  River,  the  Upper  Kittanning  coal  averages  very  nearly  3 feet 
in  thickness;  at  one  opening,  however,  it  was  only  2 feet  7 inches  as 
measured.  To  the  south  along  Stony  Creek  the  bed  gradually  grows 
thicker,  as  indicated  in  sections  5,  6,  7,  8,  9,  and  10  (fig.  6).  As 
much  as  6 feet  of  coal  was  reported  in  places  and  several  measure- 
ments of  5 feet  were  made.  (See  fig.  6.)  The  bony  character  of  the 
upper  8 inches  is  indicated  in  section  6,  and  as  a rule  the  upper  8 to 
12  inches  has  to  be  discarded.  On  Sams  Run,  east  of  Moxhom,  and 
between  Dale  and  Moxhom,  according  to  observations  made  by 
F.  B.  Peck,  the  coal  is  between  3^  and  4 feet  thick,  generally  with  a 
few  inches  of  bone  (discarded  in  mining)  at  the  top  and  a small 
bony  streak  about  midway  between  the  roof  and  floor.  At  Dale  and 
on  Solomons  Run  the  bed  is  usually  made  up  of  good  solid  coal,  vary- 
ing in  thickness  from  nearly  3 feet  to  more  than  4 feet,  here  and  there 
with  a bony  streak  near  the  middle  and  in  many  places  with  a few 
inches  of  bone  at  the  top.  On  Peggys  Run  and  in  the  exposures 
along  the  Pennsylvania  Railroad  the  coal  is  not  3 feet  thick  and  in 
places  is  less  than  2\  feet  thick.  In  Upper  Yoder  Township  the  coal 
ranges  from  3 to  4 feet  in  thickness,  often  with  one  or  two  smaller 
coals  above. 

As  a rule  the  coal  of  this  bed  is  a good  clean  product,  generally 
uniform  throughout.  In  a few  of  the  mines  the  upper  foot  of  coal 
is  reported  soft  and  the  lower  foot  harder  than  the  average.  The 
roof  of  the  coal  is  either  very  dense  shale  or  else  sandy  shale  or  sand- 
stone and  gives  no  trouble  whatsoever.  The  floor  is  usually  a few 
inches  of  firm  shale  or  clay  closely  underlain  by  the  Johnstown 
“cement”  bed.  This  cement  bed  locally  underlies  the  coal  directly. 
(See  PI.  VII,  A.)  The  coal  bed  is  uniform  in  thickness  and  few 
rolls  are  reported.  Clay  veins  are,  however,  numerous  and  in  places 
are  very  annoying.  Considerable  trouble  is  often  caused  by  gas, 
which  necessitates  the  use  of  safety  lamps. 

MIDDLE  KITTANNING  COAL. 

In  considering  the  stratigraphy  of  the  different  members  of  the 
Allegheny  formation  the  presence  of  two  small  coals  between  the 
Upper  and  Lower  Kittanning  beds  was  pointed  out  (p.  26).  The 
lower  of  these  coals  is  regarded  as  the  equivalent  of  the  Middle 
Kittanning  (C)  coal  in  the  Johnstown  district.  South  of  the  tunnel 
on  the  Baltimore  and  Ohio  Railroad  going  to  Kring  the  distance 
from  the  base  of  the  Upper  Kittanning  (Cement)  bed  to  this  coal  is 
32  feet  (section  2,  p.  45);  the  coal  here  is  only  7\  inches  thick. 
South  of  Kernville,  near  the  Eighth  Ward  mine  of  the  Citizens 
Coal  Company,  this  coal  is  11  inches  thick  and  is  about  43  feet 


JOHNSTOWN  DISTRICT. 


57 

below  the  base  of  the  Upper  Kittanning  bed  (section  4 , p.  46). 
Along  the  Pennsylvania  Railroad  near  Conemaugh  depot  the  inter- 
val between  the  Cement  bed  and  the  Middle  Kittanning  coal  is  about 
the  same — namely,  45  to  50  feet — but  the  coal  here  is  only  10^  inches 
thick  (section  7,  p.  47).  At  these  different  places  the  Middle  Kit- 
tanning coal  is  not  of  workable  thickness,  and  as  a rule  it  can  not  be 
considered  workable  in  this  district.  It  is  fairly  persistent,  how- 
ever, and  hence  serves  as  an  additional  check  on  the  identity  of  the 
beds  both  above  and  below  it.  It  has  been  opened  at  Coopersdale, 
at  the  brick  plant  of  A.  J.  Haws  & Sons  (Limited),  where  it  is  about 
25  feet  above  the  Lower  Kittanning  coal  and  shows  a thickness  of 
30  inches,  with  more  concealed.  It  is  also  said  to  be  of  workable 
thickness  at  the  head  of  Solomons  Run.  From  what  is  known  about 
it  at  present  it  can  not  be  classed  among  the  commercial  coals  of  the 
district. 

LOWER  KITTANNING  COAL. 

Name  and  'position. — The  next  lower  important  coal  in  the  Alle- 
gheny formation  is  the  Lower  Kittanning  coal.  It  is  also  known  as 
the  Miller  or  B bed  in  and  near  Johnstown.  Its  position  below  the 
Upper  Kittanning  (Cement)  bed  can  be  obtained  by  direct  measure- 
ment at  only  a very  few  points  in  the  Johnstown  district,  as  most  of 
the  operations  on  it  are  conducted  either  by  slope  or  incline.  At 
the  foot  of  the  hill  ascending  from  Kernville  to  Grandview  Cemetery, 
Johnstown,  the  interval  was  reported  to  be  98  feet,  and  where  hand 
leveled  on  Stony  Creek  south  of  the  quadrangle  it  was  just  100  feet. 
Near  the  Ingleside  Coal  Company’s  mine  it  was  reported  to  be  86 
feet.  Near  the  Franklin  mines  of  the  Cambria  Coal  Company  the 
interval  between  the  Upper  and  Lower  Kittanning  beds  was  ascer- 
tained by  means  of  a bore  hole  to  be  90  feet.  It  may  therefore  be 
safely  assumed  that  the  Lower  Kittanning  will  be  found  85  to  100 
feet  below  the  Upper  Kittanning  (Cement)  bed. 

Extent  and  development. — Immediately  about  Johnstown  the  Lower 
Kittanning  coal  is  near  to  or  below  drainage  level  and  the  mines  work- 
ing the  coal  are  either  slopes  or  shafts.  North  of  Conemaugh  River 
and  just  at  the  western  edge  of  Coopersdale  the  rise  of  the  measures 
approaching  Laurel  Ridge  brings  the  coal  above  drainage,  and  it  is 
worked  by  A.  J.  Haws  & Sons  (Limited)  at  their  brick  plant.  The 
under  clay  is  also  mined  in  connection  with  the  coal.  To  the  north 
on  Laurel  Run  the  coal  has  been  opened  in  a small  way  by  John 
Adams.  East  of  the  Haws  mine  the  coal  disappears  below  drainage 
level  and  does  not  reappear  until  it  reaches  a point  just  east  of 
Conemaugh  depot,  where  it  is  worked  by  the  Keystone  Coal  and 
Coke  Company.  From  this  point  as  far  to  the  east  as  South  Fork 
it  is  above  drainage  level  throughout  nearly  the  entire  course  of 


58  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Conemaugh  River,  varying  of  course  in  elevation  above  the  river, 
owing  to  the  Ebensburg  anticline  and  the  circuitous  course  of  the 
stream. 

South  of  Conemaugh  River  what  is  possibly  the  Lower  Kit  tanning 
coal  is  worked  at  present  by  J.  L.  Custer  well  up  on  Clapboard  Run. 
It  has  been  worked  near  the  mouth  of  the  run  by  the  Argyle  Coal 
Company,  but  considerable  difficulty  was  experienced  owing  to  the 
irregularities  in  the  bed,  which  ultimately  led  to  the  abandonment  of 
operations.  A short  distance  away,  on  Peggys  Run,  the  Cambria 
Steel  Company  has  opened  its  Franklin  No.  2 mine.  In  this  mine 
(No.  48,  PI.  I)  much  difficulty  has  been  experienced  and  much  ex- 
pensive dead  work  required  owing  to  the  irregularities  in  the  coal. 
(See  pp.  59,  60.)  In  the  city  of  Johnstown  the  Citizens  ’ Coal  Com- 
pany has  a slope  to  this  coal  bed  near  the  Adams  Street  Schoolhouse, 
and  in  Kernville  the  coal  is  worked  by  W.  J.  Williams.  The  coal 
is  above  drainage  level  for  a short  distance  on  Solomons  Run,  coming 
up  just  at  the  mouth  of  Falls  Run.  To  the  south  along  Stony  Creek 
the  coal  appears  above  drainage  level  near  Kring,  and  it  is  worked 
farther  south  on  the  east  side  of  the  creek  by  the  Ingleside  Coal 
Company.  In  the  suburbs  west  of  Johnstown — that  is,  at  Morrell- 
ville  and  on  St.  Clair  Run — the  coal  is  worked  by  W.  J.  Williams 
and  by  Robertson  & Griffith.  Thus  the  total  number  of  mines  on 
this  bed  in  this  region  is  about  ten. 

Chemical  character. — Analyses  of  this  coal  (Nos.  ll'to  14,  pp.  40-41) 
give  an  idea  of  its  composition  in  the  Johnstown  Basin. 

Like  the  coals  already  considered,  the  Lower  Kittanning  (Miller) 
coal  in  the  Johnstown  district  is  a high-carbon  coal  low  in  volatile 
matter  and  moisture.  The  ash  and  sulphur  show  considerable  varia- 
tion, but  this  may  be  accounted  for  partly  by  the  fact  that  the  sam- 
ples were  collected  at  scattered  localities.  The  ash  and  sulphur  seem 
to  be  much  in  excess  of  these  constituents  in  coals  from  the  South 
Fork  district.  As  a steam  coal  the  Lower  Kittanning  ranks  very 
high;  the  engines  on  the  Pennsylvania  Railroad  are  supplied  in  part 
with  it  from  one  of  the  mines  along  the  line.  The  coal  is  also  coked 
at  Franklin  by  the  Cambria  Steel  Company  in  by-product  ovens  for 
use  in  the  company’s  steel  plant  near  Johnstown.  It  gives  satis- 
factory results  but  has  to  be  washed  before  coking,  thereby  adding 
to  the  cost  of  the  product.  Even  with  this  additional  item  of  cost 
it  is  found  cheaper  to  coke  this  coal  on  the  ground  than  to  buy 
coke  of  better  quality  from  the  Connellsville  region. 

Occurrence  and  physical  character. — The  thickness  of  the  Lower 
Kittanning  (Miller)  coal  in  the  Johnstown  district  is  shown  in  figure  7 ; 
it  ranges  from  3^  to  4 feet,  the  latter  figure  probably  being  a maxi- 
mum for  the  Johnstown  Basin.  Except  along  Clapboard  and  Peggys 


JOHNSTOWN  DISTRICT. 


59 


runs  and  near  Franklin,  the  coal  is  on  the  whole  regular;  its  floor  rolls 
and  here  and  there  the  coal  is  cut  down  to  2 feet,  but  rarely  to  less 
than  this.  Clay  veins  are  generally  absent  and  where  present  are 
small.  In  and  about  Johnstown,  less  than  a foot  below  the  base  of 
the  main  bench  and  separated  from  it  by  shale,  there  is  commonly  a 
small  coal,  which  varies  from  7 to  24  inches,  the  latter  measurement 
being  made  at  the  mine  of  the  Somerset  and  Cambria  Coal  Company’s 
opening  on  Stony  Creek,  near  Foustwell.  Below  the  lower  coal  (or  in 
its  absence  below  the  main  bench)  occurs  a light  to  dark  drab  plastic 
clay,  ranging  from  3 to  6 feet  in  thickness.  It  was  observed  that 
where  the  clay  was  at  a maximum  the  coal  appeared  in  a single 
bench,  with  the  lower  part  bony ; but  it  can  not  be  stated  that  this 
condition  is  the  usual  one.  The  clay  is  of  great  importance  near 
Johnstown.  (See  pp.  117-118.)  The  coal  itself  is  in  general  entirely 


Figure  7.— Sections  of  the  Lower  Kittanning  (Miller  or  B)  coal  in  the  Johnstown  district. 
Scale,  1 inch=5  feet. 


1.  John  Adams,  Laurel  Run. 

2.  A.  J.  Haws  & Sons,  Coopersdale  mine. 

3.  A.  J.  Haws  & Sons,  shaft  at  brick  plant. 

4.  W.  J.  Williams,  Kernville. 

5.  Citizens’  Coal  Company,  Green  Hill  mine. 

6.  Cambria  Steel  Company,  Franklin  No.  2. 

7.  Cambria  Steel  Company,  Franklin  No.  2,  outlet  on  Clapboard  Run. 

8.  Keystone  Coal  and  Coke  Company,  Conemaugh  slope. 

9.  Ingleside  Coal  Company. 

10.  Robertson  & Griffith,  St.  Clair  Run. 


free  from  partings  and  is  uniform  from  roof  to  floor.  The  roof  is 
massive  sandstone,  tough  shale,  or  sandy  shale,  requiring  little  or  no 
timbering,  and  there  is  no  draw  slate  reported. 

At  Franklin  and  on  Clapboard  Run,  on  the  other  hand,  the  Lower 
Kittanning  coal  is  erratic,  and  much  difficulty  has  been  experienced 
in  mining  on  account  of  the  irregular  character  of  the  floor.  These 
irregularities  are  termed  faults  by  the  miners,  but  they  are  not  faults 
in  the  geologic  sense.  The  coal  in  this  locality  may  be  6 feet  thick 
in  one  place  and  only  15  inches  thick  a few  feet  away,  and  over 
small  areas  it  is  completely  absent.  It  is  believed  that  this  singular 


60  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINItY. 

occurrence  is  due  to  peculiar  conditions  of  sedimentation  during  or 
subsequent  to  its  original  deposition  in  this  locality,  and  not  to 
subsequent  movement,  and  that  the  trouble  will  be  found  to  be 
only  local  and  will  disappear  to  the  south.  In  confirmation  of  this 
belief  may  be  cited  two  drill  holes,  one  on  the  Frankstown  road  and 
the  other  near  the  head  of  Peggys  Run,  in  which  the  Lower  Kittan- 
ning coal  is  normally  developed.  So  far  as  known,  the  coals  above 
the  Lower  Kittanning  (Miller)  are  normal  in  their  occurrence;  if 
the  cause  for  the  erratic  conditions  in  the  Lower  Kittanning  were 
regional,  the  Upper  Kittanning  (Cement)  coal,  which  is  worked  at 
higher  levels  in  the  same  hills,  would  probably  be  irregular  likewise. 
The  slight  folds  or  rolls  in  the  structure  observed  along  the  Penn- 
sylvania Railroad  near  East  Conemaugh  are  considered  to  have  had 
nothing  to  do  with  the  peculiar  conditions  just  described.  These 
irregularities  have  led  to  much  expensive  dead  work  near  Franklin 
and  have  caused  the  abandonment  of  large  operations  on  Clapboard 
Run. 

LOWER  ALLEGHENY  COALS. 

Coals  lower  than  the  Lower  Kittanning  and  yet  in  the  Allegheny 
formation  are  exposed  in  this  district.  At  Coopersdale  the  top  of 
the  Pottsville  formation  appears  at  road  level  just  west  of  the  brick 
plant  of  A.  J.  Haws  & Sons  (Limited).  Just  above,  two  small  coal 
beds,  each  measuring  less  than  2\  feet,  are  exposed,  separated  by 
about  10  feet  of  dark  shale.  The  section  is  given  on  page  23.  These 
coals  probably  correspond  to  the  Brookville  (A)  and  Clarion  (A') 
of  the  Allegheny  Valley.  One  of  these,  probably  the  lower  (Brook- 
ville), is  exposed  on  Clapboard  Run.  The  Lower  Kittanning  seam 
has  been  opened  along  this  run,  and  about  70  feet  below  it  a coal  has 
been  worked  which  is  considered  the  Brookville  or  a coal  very  close 
to  it.  Two  sections  of  this  coal  are  as  follows: 


Bony  coal 

Bone 

Coal 


Sections  of  Brookville  coal  on  Clapboard  Run. 
Ft.  in. 

1 8 Bone  or  shale 

1 Coal 

1 8 Bone 

Coal 

Bone  or  shale 

Coal 


Ft.  in. 
9 
3 

2 

G 

1 

1 7 


These  sections  are  very  similar,  showing  an  upper  bench  from  18 J 
to  20  inches  in  thickness,  mostly  of  bone  and  of  no  value,  and  a lower 
bench  19  or  20  inches  thick.  The  coal  has  no  value  along  this  run. 

South  of  the  quadrangle,  between  the  mouth  of  Paint  Creek  and 
Foustwell,  the  lower  part  of  the  Allegheny,  together  with  the  whole 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


61 


of  the  Pottsville  and  a large  part  of  the  Mauch  Chunk  formation,  is 
brought  above  drainage  level  on  the  flanks  of  the  Ebensburg  or  Via- 
duct anticline.  The  section  on  page  27  shows  a 
coal  10  to  15  feet  above  the  massive  sandstone  at 
the  top  of  the  Pottsville  and  separated  from  it 
by  shale  and  sandstone.  It  is  quite  possible  that 
this  may  be  the  Clarion  coal.  At  least  it  is  one 
of  the  Brookville-Clarion  coal  group.  (See  fig.  8.) 

POTTSVILLE  COALS. 

The  Pottsville  formation  lies  below  the  Allegheny 
formation  and,  as  indicated  on  page  28,  consists  of 
an  upper  and  a lower  sandstone  member  with  an 
intervening  shale  member.  This  shale  in  many 
places  carries  a coal  known  as  the  Mercer.  The 
coal  appearing  between  the  tipple  of  the  Ingleside  Coal  Company  and 
Kring,  on  Stony  Creek  south  of  Johnstown,  is  considered  to  belong  in 
the  Mercer  coal  group.  The  section  is  as  follows  (see  also  fig.  2) : 

Section  of  Mercer  coal  south  of  Kring. 


Ft.  in. 

Black  shale 5 6 

Coal 9 

Pyritiferous  dark  sandstone 1-2 

Coal 6 

Shale 2 

Coal 9 

Coal  and  bone 11 

Black  shale . . 3-4 

Coal 4 

Bone 

Clay 1 


The  coal  is  so  badly  broken  that  it  can  not  be  considered  among  the 
workable  beds  of  the  district. 

Near  Sheridan  the  Mercer  coal  is  about  a foot  thick.  (See  p.  119.) 

SOUTH  FORK-MINERAL  POINT  DISTRICT. 

EXTENT. 

In  the  South  Fork-Mineral  Point  district  will  be  included  all  the 
coal  occurrences  between,  in,  and  near  the  two  towns  named.  The 
mining  operations  extend  from  Ehrenfeld  on  the  east  to  the  point 
where  Conemaugh  River  makes  a sharp  bend  to  the  south,  about  2 
miles  west  of  Mineral  Point.  Operations  are  conducted  on  both 
sides  of  the  river.  The  openings  are  confined  to  the  immediate 
river  valley,  but  the  workings  in  many  of  the  larger  mines  are  very 
extensive  and  have  been  pushed  back  into  the  hills  a long  distance 
from  the  river. 


Figure  8.— Section  of  the 
Clarion  (A')  coal  along 
Baltimore  and  Ohio 
Railroad  near  southern 
edge  of  Johnstown 
quadrangle.  Scale,  1 
inch  = 5 feet. 


62  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


GEOLOGIC  POSITION  OF  COALS. 

The  three  formations  which  are  of  economic  interest  in  the  district 
are  the  Conemaugh,  Allegheny,  and  Pottsville.  The  dips  near  South 
Fork  are  steep  and  the  rock  exposures  are  too  imperfect  to  permit 
complete  and  detailed  sections.  North  and  south  of  Conemaugh 
River,  however,  diamond-drill  holes  have  been  put  down  and  the  rec- 
ords have  apparently  been  carefully  kept.  Opportunity  was  afforded 
also  for  a measurement  of  the  rocks  in  the  shaft  of  the  Pennsylvania, 
Beech  Creek,  and  Eastern  Coal  Company  near  New  Germany.  A 
very  clear  idea,  therefore,  of  the  rocks  as  far  down  in  the  section  as 
the  Lower  Kittanning  (Miller)  coal  has  been  obtained. 

On  South  Fork  of  Conemaugh  River,  near  the  northernmost  cottage 
of  the  group  near  the  old  dam  site,  the  interval  between  the  Upper 
Freeport  and  Lower  Kittanning  coals  is  206  feet.  In  the  shaft  at  New 
Germany  the  interval  between  the  two  coals  is  145  feet,  a decrease  to 
the  north  of  61  feet.  It  is  known  that  this  decrease  in  the  interval 
takes  place  within  a distance  of  4§  miles,  and  it  is  possible  that  it  may 
occur  within  a shorter  distance. 

CONEMAUGH  COALS. 

COAL  NEAR  SUMMERHILL. 

Northwest  of  Summerhill,  at  an  elevation  of  1,800  feet,  a coal  has 
been  opened  by  the  side  of  the  public  road.  It  is  reported  to  be 
exactly  300  feet  above  the  Upper  Freeport  (Lemon  or  E)  coal.  The 
openings  have  entirely  fallen  in  and  no  opportunity  was  afforded  to 
measure  the  thickness  or  ascertain  the  character  of  the  coal.  The 
information  was  received  that  about  40  acres  of  territory  had  been 
worked  out  and  that  the  coal  was  4 feet  thick.  A measurement  of 
the  thickness  of  the  part  of  the  coal  exposed  along  the  roadside  fully 
corroborates  this  information. 

This  occurrence  is  probably  that  described  by  Platt  under  the 
heading  “ Brown’s  mine,  near  Summerhill.”  Platt’s  description  is 
as  follows : a 

Northeast  of  the  outcrop  [of  the  E coal?]  the  hill  rises  steadily  for  250  feet,  and  near 
the  top  Mr.  Brown  opened  up  a bed  of  coal  unlike,  both  in  character  and  in  position 
geologically,  any  other  coal  thus  far  known  in  Cambria  County.  It  overlies  the  Upper 
Freeport  bed  (E)  certainly  by  as  much  as  200  feet;  but  the  intervening  measures  are 
concealed,  and  their  character  is  therefore  almost  wholly  unknown. 

The  bed  has  very  little  cover  and  is  irregular  and  uneven,  both  roof  and  floor  under- 
going frequent  changes,  sometimes  within  a few  yards.  Moreover,  the  thickness  of  the 
bed  has  been  very  seriously  affected  by  “horsebacks”  and  “clay  veins,”  the  coal 
varying  in  width  all  the  way  from  4 feet  to  as  many  inches. 

Two  drifts  were  started  in  on  the  bed  at  the  outcrop ; one  gangway  is  driven  north- 
west and  the  other  northeast.  In  both  entries  there  is  a sharp  rise,  that  to  the  north- 
east being  due  to  a local  roll  in  the  rocks  of  tolerably  wide  sweep. 


a Second  Geol.  Survey  Pennsylvania,  Rept.  H2,  1877,  pp.  38-40. 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


63 


The  following  measurements  of  the  bed,  made  in  the  northeast  gangway,  will  serve 
to  give  a clearer  expression  to  the  actual  condition  of  things: 

Section  made  near  mouth  of  mine. 

Ft.  in. 


Roof,  ‘ 1 black  slate  ” 1 

Coal,  compact  and  of  cuboidal  structure 1 6 

Coal,  friable  and  of  columnar  structure 4 

Coal,  cuboidal  structure 2 10 

Floor,  “slate,”  alternating  with  sandstone. 

Section  made  60  feet  beyond  last. 

Sandstone.  Ft.  in. 

Slate 6 

Coal 2 

Slate 2 

Coal 1 3 


Between  these  two  measurements  a “clay  vein”  intervenes,  cutting  out  the  coal 
almost  entirely  for  a short  distance.  The  bed  then  resumes  its  full  height  as  given 
above,  but  diminishes  steadily  in  going  northeast,  until  at  the  end  of  the  entry  the 
coal  is  no  longer  of  workable  size,  as  follows: 


Roof,  sandstone.  Ft.  in. 

Coal 1 6 

Sandstone  floor. 


At  this  point  operations  were  brought  to  a close. 

In  the  northwest  mine  the  coal  attains  its  greatest  thickness,  but  is  everywhere 
slaty  and  poor;  it  shows,  however,  throughout,  the  same  horizontal  crystallization 
already  noted  in  connection  with  the  other  mine.  The  northwest  entry  was  driven 
in  several  hundred  yards,  but  with  practically  the  same  results  as  attended  the  opera- 
tions elsewhere.  These  continued  troubles  naturally  led  to  the  abandonment  of  the 
mines. 

The  bed  is  represented  only  in  the  tops  of  the  highest  hills  and  covers  a very  limited 
area.  The  rise  in  the  rocks  carries  it  into  the  air  a short  distance  west  of  Brown’s 
openings,  and  east  of  the  synclinal  axis  it  is  not  known  to  occur. 

Considering  the  geological  horizon  of  the  bed,  together  with  the  slaty  character  of 
the  coal  from  it,  it  is  apparent  that  this  is  one  of  the  seams  of  the  Barren  Measures,  of 
which  there  are  several,  usually  thin  and  unimportant,  but  here,  and  confined  per- 
haps to  this  immediate  territory,  of  abnormal  thickness  and  width. 

The  bed  also  undergoes  such  marked  changes  in  point  of  character  that  no  one 
specimen  would  fairly  represent  the  average  run  of  the  mine.  In  the  main,  however, 
the  coal  is  poor,  being  heavily  loaded  with  earthy  matter  and  other  impurities.  But 
along  the  center  of  the  bed  ranges  not  infrequently  a narrow  belt  of  soft,  bright,  rich 
clean  coal,  the  limits  of  which  are  clearly  defined  both  above  and  below  by  benches 
of  smooth,  tough,  slaty  coal.  * * * 

Two  analyses  of  the  coal  were  therefore  made  of  specimens  selected  and  forwarded 
to  Harrisburg  by  the  owners  of  the  property,  the  Messrs.  Brown,  of  Summerhill. 
The  first  analysis  represents  the  small  bench  of  soft  friable  coal,  and  reads  as  follows 


(D.  McCreath): 

Water  at  225° 0.  820 

Volatile  matter 19. 155 

Fixed  carbon 70.175 

Sulphur 445 

Ash.,, 9.405 


100.  000 


64  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Coke,  per  cent,  80.025;  color  of  ash,  gray.  The  coal  is  bright,  tender,  and  seamed 
with  charcoal  and  pyrites. 

The  other  analysis  may  be  said  to  represent  the  condition  of  the  greater  portion  of 
the  bed.  The  large  percentage  of  ash,  nearly  one-fifth  of  the  whole,  gives  to  this  coal 
its  firmness  and  compactness  and  also  its  slightly  conchoidal  fracture  and  dull  luster, 
but  at  the  same  time  it  ruins  the  bed  totally  for  all  practical  purposes.  The  analysis 
also  shows  that  this  cannel  slate  is  more  sulphurous  than  the  bench  of  soft  coal  in  the 
center  of  the  bed.  The  analysis  is  as  follows  (D.  McCreath): 


Water  at  225° 0.  550 

Volatile  matter 17.  325 

Fixed  carbon 61.  632 

Sulphur 1.  033 

Ash 19.  460 


100.  000 

Coke,  per  cent,  82.125;  color  of  ash,  gray.  The  coal  is  exceedingly  compact,  has  a 
dull,  resinous  luster  generally,  but  carries  seams  of  bright  crystalline  coal. 

GALLITZIN  COAL. 

South  of  South  Fork  a coal  appears  in  the  sections  about  115  feet 
above  the  Upper  Freeport  (Lemon  or  E)  bed.  From  its  interval  this 
is  probably  the  representative  of  the  Gallitzin  bed.  It  is  not  work- 
able, as  it  is  rarely  more  than  a foot  thick.  North  of  South  Fork 
this  coal  is  about  65  feet  above  the  Upper  Freeport  coal.  Another 
coal,  possibly  the  Mahoning,  appears  below  it  in  the  section;  this 
likewise  is  not  workable  near  South  Fork. 

ALLEGHENY  COALS. 

Four  coals  have  been  worked  in  the  Allegheny  formation  in  the 
South  Fork-Mineral  Point  district.  They  are  (1)  the  Upper  Free- 
port or  E coal,  which  is  known  near  South  Fork  and  also  along  the 
eastern  margin  of  the  Wilmore  Basin  as  the  Lemon  coal;  (2)  the 
Upper  Kittanning  or  Cement  coal;  (3)  the  Lower  Kittanning,  Miller, 
or  White  Ash  coal;  and  (4)  the  Brookville,  usually  referred  to  as 
the  Dirty  A coal.  The  first  three  are  of  greatest  importance  in  this 
district. 

UPPER  FREEPORT  COAL. 

Name  and  'position. — As  stated  above,  the  Upper  Freeport  coal  is 
known  at  South  Fork  as  the  Lemon  coal.  It  is  also  sometimes  called 
the  E bed,  having  been  so  termed  by  the  geologists  of  the  Second 
Geological  Survey  of  Pennsylvania.  It  is  also  often  referred  to  as 
the  Four-foot  coal.  The  position  of  this  coal  at  the  top  of  the 
Allegheny  and  its  relations  to  the  lower  Allegheny  coals  are  shown  in 
figure  2.  Its  position  with  reference  to  the  Mahoning  sandstone  in 
the  South  Fork  district  is  indicated  in  the  following  section  measured 
at  Ehrenfeld : 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


65 


Section  of  Upper  Freeport  {Lemon)  coal  and  associated  beds  at  Ehrenfeld , Pa. 


Ft.  in. 

Shale 15 

Shale,  olive  and  drab,  locally  sandy  (Upper  Mahoning?) 30 

Coal  (Mahoning,  upper  bench) 4-5 

Shale 8 

Shale,  black 2 

Shale,  blue  and  black 1 

Coal  (Mahoning,  lower  bench) 2 

Shale 15 

Shale,  blue,  with  alternating  layers  of  fine-grained  sandstone..  20 

Sandstone,  massive  (Mahoning) 20 

Coal,  1 foot  Ilf  inches] 

Bone,  2 inches lUpper  Freeport  coal 3 9f 

Coal,  1 foot  8 inches. . J 

Clay,  with  limestone  nodules  in  lower  foot 2 

Limestone,  irregularly  bedded  (Upper  Freeport) lf-3 

Fire  clay  in  places 1± 

Shale 15+ 


Extent  and  development. — The  Upper  Freeport  coal  appears  above 
drainage  level  just  east  of  Ehrenfeld,  and  has  been  opened  at  rail- 
road level  by  the  Pennsylvania,  Beech  Creek,  and  Eastern  Coal  Com- 
pany at  its  No.  8 opening.  Not  far  to  the  west,  but  higher  in  the 
hill  owing  to  the  rapid  rise  of  the  beds  westward,  is  located  mine 
No.  6 of  the  same  company.  This  mine  was  not  being  worked  in 
the  summer  of  1906,  at  the  time  of  visit.  West  of  Mineral  Point 
this  coal  is  present  in  the  hills  bordering  Conemaugh  River,  but  at 
varying  distances  from  it.  (See  PL  I.)  It  has  been  opened  in  a 
small  way  in  one  or  two  places,  but  where  seen  the  openings  had 
fallen  in. 

South  of  Conemaugh  River  it  has  been  worked  in  and  near  South 
Fork  by  the  South  Fork  Mining  Company,  and  on  the  west  side  of 
South  Fork  of  the  Conemaugh  by  O.  M.  and  H.  C.  Stineman.  It  is 
also  present  in  the  hills  along  the  south  side  of  the  river,  but  it  has 
been  hardly  touched  there  up  to  the  present  time. 

Chemical  character. — Analysis  No.  3,  page  40,  shows  the  character 
of  this  coal  near  South  Fork.  It  compares  favorably  with  the  other 
coals  in  the  Johnstown  quadrangle,  and  the  analysis  shows  the  normal 
high  carbon  content,  with  low  volatile  combustible  matter.  Moisture 
and  ash  are  also  low,  but  sulphur  is  high.  The  product  from  this  coal 
bed  is  used  chiefly  for  steaming  purposes.  It  is  also  coked  in  beehive 
ovens  at  Cresson,  Gallitzin,  and  Bennington  with  satisfactory  results. 
Its  composition  along  certain  parts  of  the  Allegheny  Front — at  Gal- 
litzin, for  instance — is  different  from  that  of  the  coal  near  South  Fork, 
as  the  following  analyses  will  show.  The  percentage  of  fixed  carbon 
is  lower  and  that  of  volatile  matter  higher  in  the  Ebensburg  region 
69516°— Bull.  447—11 5 


66  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


than  on  the  west  side  of  the  basin  at  South  Fork.  The  coal  collected 
at  Sonman,  Puritan,  and  Dunlo,  however,  is  very  much  the  same  in 
composition  as  that  near  South  Fork  and  Johnstown. 

Analyses  of  Upper  Freeport  coal  in  Ebensburg  quadrangle. a 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

Moisture  

0.52 

0.63 

0.  41 

1.41 

0. 43 

0. 47 

0.  .41 

Fixed  carbon  

66. 00 

64.  43 

74.71 

71.26 

72.89 

74. 17 

73. 17 

Volatile  matter 

26. 59 

27.92 

19.  41 

20.05 

17.77 

18.  44 

17.83 

Ash 

6.  89 

7.02 

5.47 

7.28 

8.91 

6.  92 

8. 59 

Sulphur 

1.21 

.94 

1.38 

3. 34 

1.83 

1.71 

1.53 

a Ebensburg  folio  (No.  133),  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1905,  p.  9.  The  samples  whose  analy- 
ses are  given  above  were  collected  by  Charles  Butts. 

1,  2.  Pennsylvania,  Beech  Creek,  and  Eastern  Coal  Company,  Gallitzin.  W.  T.  Schaller,  analyst. 

3.  Shoemaker  Coal  Company,  Sonman.  W.  T.  Schaller,  analyst. 

4.  G.  Pearse  & Sons,  Puritan.  W.  T.  Schaller,  analyst. 

5.  6,  7.  Mountain  Coal  Company,  Dunlo.  Analysis  made  at  Metallurgical  Laboratory,  Pittsburg,  Pa. 

Occurrence  and  physical  character.-*- The  Upper  Freeport  coal  about 
South  Fork  may  occur  in  either  two  or  three  benches,  of  which  only 


Figure  9. — Sections  of  the  Upper  Freeport  (E  or  Lemon)  coal  near  South  Fork.  Scale,  1 inch=5feet. 

1,  O.  M.  Stineman  No.  3;  2,  H.  C.  Stineman  No.  5;  3,  Pennsylvania,  Beech  Creek  and  Eastern  Coal  Com- 
pany No.  8;  4,  natural  exposure  in  railroad  cut  at  Ehrenfeld;  5,  South  Fork  Coal  Mining  Company  No.  2 


Figure  10. — Sections  of  the  Upper  Freeport  coal  along  the  southeastern  margin  of  the  Wilmore  Basin 
(after  Butts).  Scale,  1 inch=5  feet. 

1,  Webster  No.  11  mine,  southeast  of  Gallitzin,  Pa.;  2,  Shoemaker  mine,  Sonman;  3,  Hopfer’s  mine, 
Trout  Run;  4,  George  Pearse  & Sons,  Puritan;  5,  Beaverdam  Run,  near  Pavia  road;  6,  Logan  Coal  Com- 
pany, Beaverdale;  7,  Dunlo. 

the  two  lower  are  workable,  and  in  this  respect  it  differs  essentially 
from  the  same  coal  about  Johnstown.  At  Ehrenfeld  and  at  opening 
No.  8 of  the  Pennsylvania,  Beech  Creek,  and  Eastern  Coal  Company, 
on  the  opposite  side  of  Conemaugh  River,  only  two  benches  were 
observed,  and  the  upper  bench  is  for  the  most  part  very  much  thicker 
than  the  corresponding  middle  bench  at  places  where  three  are 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


67 


present.  The  upper  of  the  workable  benches  ranges  in  thickness 
from  1 foot  to  2 feet  and  the  lower  bench  from  1J  to  2 feet.  The 
bone  or  shale  between  the  two  main  benches  ranges  from  half  an  inch 
to  2 inches.  It  is  very  persistent  in  this  district  and  is  usually  pres- 
ent also  in  this  bed  along  the  southeast  margin  of  the  Wilmore  Basin. 
Figures  9 and  10  show  the  general  similarity  of  this  coal  bed  on  both 
sides  of  the  Wilmore  Basin. 

LOWER  FREEPORT  COAL. 

The  next  lower  coal  in  the  South  Fork  district  is  the  Lower  Free- 
port coal,  which  lies  from  40  to  50  feet  below  the  Upper  Freeport 
coal.  It  is  persistent  and  is  shown  in  most  of  the  diamond-drill 
records,  but  it  has  not  been  developed  in  this  district.  Locally  it  is 
of  workable  thickness;  in  some  of  the  well  records  it  measures  as 
much  as  2\  feet  solid  coal  with  no  partings;  in  others  it  consists  of 
two  benches  separated  by  a thin  binder.  The  two  benches  taken 
together  would  constitute  a workable  bed.  In  most  of  the  sections 
studied  it  is  so  badly  broken  up  or  so  thin  as  to  be  of  no  value;  and 
it  therefore  can  not  be  classed  among  the  commercial  coals  in  this 
district  at  present. 

UPPER  KITTANNING  (CEMENT)  COAL. 

Name  and  'position . — The  next  lower  coal — the  Upper  Kittanning 
(Cement)  bed — is  an  important  coal  near  South  Fork.  It  corresponds 
to  the  same  bed  about  Johnstown,  though  it  is  not  at  this  time  so  im- 
portant as  the  coal  in  that  district.  It  occurs  nearly  midway  between 
the  Upper  Freeport  (Lemon  or  E)  coal  and  the  Lower  Kittanning 
(Miller)  bed.  North  of  Conemaugli  River,  therefore,  where  the  inter- 
val between  these  two  coals  is  only  145  feet  (as  near  New  Germany), 
it  occurs  about  67  feet  below  the  Upper  Freeport  coal  and  about  75 
feet  above  the  Lower  Kittanning.  South  of  the  river,  where  the 
interval  between  the  Upper  Freeport  and  Lower  Kittanning  is 
approximately  200  feet,  it  is  again  about  midway  between  the  two, 
its  distance  below  the  former  and  above  the  latter  ranging  from  92 
to  105  feet. 

Extent  and  development. — The  Upper  Kittanning  is  worked  for 
local  supply  in  the  town  of  South  Fork  by  Robert  A.  Giles  and 
Charles  Hutzel.  Other  (abandoned)  banks  in  the  town  were  observed. 
West  of  the  town  and  on  the  west  side  of  South  Fork  it  is  worked 
on  a considerable  scale  by  H.  C.  and  O.  M.  Stineman.  The  coal  is 
present  in  the  hills  westward  to  Mineral  Point  and  beyond.  Near 
Mineral  Point  two  small  mines  on  this  coal  bed  belong  to  H.  W. 
Gillan.  (See  PI.  IV,  B.) 

Chemical  character. — Analysis  No.  5,  page  40,  indicates  the  com- 
position of  this  coal  in  South  Fork.  The  coal  is  bright  and  lustrous 


68  MINERAL  RESOURCES  OP  JOHNSTOWN,  PA.,  AND  VICINITY. 

and  the  analysis  shows  it  to  be  on  a par  with  the  corresponding  coal 
in  the  Johnstown  district.  Both  its  ash  and  sulphur  average  below 
those  of  the  coal  in  that  district,  but  in  other  respects  the  analyses 
are  very  similar. 

To  the  east,  in  the  Ebensburg  quadrangle,  this  coal  is  locally 
workable  and  has  been  opened  and  worked  by  G.  Pearse  & Sons  at 
Puritan,  on  Trout  Run.  The  composition  of  the  coal  here,  as  shown 
in  the  table  below,  is  about  the  same  as  it  is  farther  west,  about 
South  Fork;  but  analyses  of  the  two  samples  collected  in  the  same 
mine  show  considerable  divergence. 


Analyses  of  Upper  Kittanning  coal  at  Puritan. 
[W.  T.  Schaller,  analyst.] 


1. 

2. 

Moisture 

1.70 

0.52 

Volatile  matter 

19. 28 

22.00 

Fixed  carbon 

71.19 

67.49 

Ash 

7.83 

9.  99 

Sulphur 

1.60 

3. 47 

Occurrence  and  'physical  character. — In  thickness  the  coal  ranges 
from  3 to  3J  feet,  usually  without  any  partings,  and  has  a hard  shale 
roof  which  gives  no  trouble.  There  is  in  places  a few  inches  of  bone 


2 3 5 e 8 


Figure  11.— Sections  of  the  Upper  Kittanning  (Cement  or  C')  coal  in  the  South  Fork-Mineral  Point 

district.  Scale,  1 inch= 5 feet. 

1,  H.  C.  Stineman  No.  6,  South  Fork;  2,  O.  M.  Stineman,  No.  3J,  South  Fork;  3,  Robert  A.  Giles,  South 
Fork;  4,  Charles  Hutzel,  South  Fork;  5,  Old  opening,  southern  partof  South  Fork;  6,  7,  H.  W.  Gillan,near 
Mineral  Point;  8,  Salt  Lick  Run. 

at  the  top,  which  is  discarded  in  mining.  The  lower  part  of  the  coal  is 
locally  bony.  Below  this,  and  in  its  absence  directly  below  the  coal, 
there  is  a band  of  clay,  ranging  from  a few  inches  to  more  than 
2 feet.  Below  the  clay,  or  just  below  the  coal  itself,  is  found  a bed 
of  limestone  or  cement  rock — the  Johnstown  limestone  member — 
measuring  in  places  as  much  as  4 feet. 

Figure  11  indicates  graphically  what  has  been  outlined  above.  In 
the  area  to  the  east  the  coal  is  locally  workable,  and  where  exploited 
by  G.  Pearse  & Sons,  on  Trout  Run,  on  the  east  side  of  the  basin, 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


69 


in  the  Ebensburg  quadrangle,  its  thickness  is  very  much  the  same  as 
near  South  Fork.  At  Bennington  it  is  2 feet  10  inches  thick;  in  the 
Sonman  shaft  it  is  2 feet;  in  the  Yellow  Run  shaft  2 feet  6 inches;  and 
in  a diamond-drill  hole  of  the  Henriette  Mining  Company,  south  of 
Llanfair,  it  is  1 foot  thick.  On  the  east  side  of  the  basin,  therefore, 
it  can  not  be  considered  more  than  locally  workable.  On  the  west 
side  of  the  basin  it  may  be  regarded  as  among  the  future  important 
coals,  both  near  South  Fork  and  in  the  region  to  the  south,  where 
considerable  exploratory  work  with  the  diamond  drill  has  showed  this 
coal  to  be  3 feet  or  more  in  thickness. 

LOWER  KITTANNING  (MILLER)  COAL. 

Name  and  'position. — The  Lower  Kittanning,  Miller,  B,  or  White  Ash 
bed  is  the  most  important  coal  in  the  South  Fork-Mineral  Point 
district.  Immediately  about  South  Fork  it  lies  160  feet  below  the 
Upper  Freeport  bed;  elsewhere  it  ranges  from  145  to  200  feet  below 
the  Upper  Freeport  coal  (see  p.  24)  and  about  half  as  much  below 
the  Upper  Kittanning  (Cement)  bed.  Its  position,  approximately 
55  to  65  feet  above  the  top  of  the  Pottsville  (or  “conglomerate  rock/’ 
as  the  Pottsville  is  popularly  called),  should  serve  to  locate  and 
identify  it  with  little  trouble  in  the  South  Fork-Mineral  Point  district. 

Extent  and  development. — North  of  Conemaugh  River  the  coal  has 
been  opened  by  the  Pennsylvania,  Beech  Creek,  and  Eastern  Coal 
Company  and  worked  at  its  No.  3 and  No.  5 mines,  the  workings  in 
the  latter  being  on  the  dip  of  the  bed.  Farther  west  the  Priscilla 
Coal  Company  is  working  the  same  bed,  and  still  beyond,  near  the 
Ebensburg  (Viaduct)  anticlinal  axis,  are  the  openings  of  the  Keystone 
Coal  and  Coke  Company,  called  Argyle  Nos.  1 and  2 mines.  There 
are  also  a few  abandoned  mines  on  the  Lower  Kittanning  bed  north 
of  Conemaugh  River,  and  to  judge  from  the  culm  heaps  at  their 
tipples  large  bodies  of  coal  have  been  removed  from  them. 

South  of  the  river  and  west  of  South  Fork  the  workings  on  the 
Lower  Kittanning  coal  are  extensive.  The  mines  here  include 
collieries  Nos.  2 and  4 of  the  Stineman  Coal  and  Coke  Company  and 
colliery  No.  1 of  the  Stineman  Coal  Mining  Company.  To  the  east 
and  in  the  town  itself  are  the  workings  of  the  South  Fork  Coal  Mining 
Company.  The  magnitude  of  the  coal  industry  at  South  Fork  may 
be  judged  from  the  fact  that  in  1905  there  were  produced  in  these 
mines  1,400,000  tons  of  coal,  valued  at  $1,500,000. 

Chemical  character. — Analyses  Nos. 15, 16, 28,  an  d29  (pp.  40-42)  give 
an  excellent  idea  of  the  high  grade  of  this  coal  as  mined  near  South 
Fork.  The  analyses  below  give  an  idea  of  its  composition  in  the 
Ebensburg  quadrangle,  on  the  southeast  flank  of  the  Wilmore  Basin. 


70  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Analyses  of  Lower  Kittanning  ( Miller ) coal  in  the  Ebenshurg  quadrangle .a 
[Air-dried  samples;  W.  T.  Schaller,  analyst.] 


1. 

2. 

3. 

4. 

5. 

6. 

7. 

Moisture 

0.53 

0.32 

0. 57 

0. 38 

0.36 

0.35 

0. 43 

Volatile  matter 

26.90 

21.97 

23.52 

19.  44 

20.46 

17.81 

19. 41 

Fixed  carbon 

63.52 

71.38 

69.64 

74.  28 

72.  76 

74.  28 

75. 78 

Ash 

9.  05 

6. 33 

6.  27 

5. 90 

6.42 

7.  56 

4. 38 

Sulphur 

1.21 

.68 

.99 

.72 

1.74 

3. 14 

.76 

a Ebensburg  folio  (No.  133),  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey,  1905,  p.  9. 


1.  Reed  & Bradley  mine,  Bennington. 

2,  3.  Lilly  Mining  Company,  Bear  Rock  Rim. 

4.  A.  C.  Blowers,  Bens  Creek. 

5,  6.  Alton  Coal  Company,  Lloydell. 

7.  Henriette  Coal  Company,  near  Llanfair. 

1 to  6 collected  by  Charles  Butts;  7 by  W.  C.  Phalen. 

From  the  analyses  (pp.  40-42)  it  appears  that  the  fixed  carbon  in 
the  samples  collected  in  the  Johnstown  quadrangle,  near  South  Fork, 
ranges  from  74  to  more  than  78  per  cent,  with  volatile  matter  ranging 
from  14  to  more  than  16  per  cent.  The  moisture  of  the  samples  as 
received  at  the  laboratory  is  low,  not  exceeding  3.5  per  cent.  The 
samples  from  South  Fork  are  notably  low  in  sulphur  and  ash  and 
show  the  excellent  character  of  the  Lower  Kittanning  (Miller)  coal 
in  this  part  of  the  Wilmore  Basin.  The  samples  collected  from  the 
Ebensburg  quadrangle  by  Charles  Butts  and  W.  C.  Phalen  during  the 
summer  of  1903  were  analyzed  in  the  chemical  laboratory  of  the 
Survey  at  Washington  and  not  in  the  laboratory  of  the  technologic 
branch  of  the  Survey  at  St.  Louis.  The  results  of  analyses  are  there- 
fore not  strictly  comparable  with  the  results  of  analyses  from  South 
Fork  (pp.  40-42).  The  former  show  more  diversity  in  composition-, 
as  would  naturally  be  expected  when  the  scattered  places  from  which 
the  samples  were  collected  are  considered.  The  general  similarity 
of  the  results,  however,  is  noteworthy,  as  is  also  the  low  content  in 
sulphur  and  ash.  The  second  sample  collected  from  the  Alton  Coal 
Company’s  mine  at  Lloydell  (No.  6,  above)  seems  to  be  entirely 
exceptional  regarding  its  sulphur  content,  and  it  is  probable  that  a 
“sulphur  ball”  found  its  way  into  the  sample  without  being  suspected. 

Steaming  tests. — As  a steam  coal  the  Lower  Kittanning  (Miller) 
coal  from  the  South  Fork  district  ranks  among  the  very  best  of 
western  Pennsylvania  and  probably  equals  in  steaming  value  any 
other  steam  coal  in  this  part  of  the  State.  (See  comparative  tables, 
p.  37.) 

In  the  following  tables  are  given  the  results  of  tests  on  run-of- 
mine  coal  loaded  under  the  supervision  of  J.  S.  Burrows,  formerly 
of  the  Survey,  collected  from  No.  3 mine  of  the  Pennsylvania,  Beech 
Creek,  and  Eastern  Coal  Company,  at  Ehrenfeld.  One  coking  test, 
five  steaming  tests,  and  one  producer-gas  test  were  made  on  the  car- 


SOUTH  FORK-MINERAL  POINT  DISTRICT, 


71 


load  sample  collected.®  A steaming  test  was  also  made  on  this  sample 
mixed  with  eoal  from  the  Darby  mine  of  the  Darby  Coal  and  Coke 
Company,  at  Darby,  Lee  County,  Va.,  but  the  results  of  this  test 
are  not  given  in  the  bulletin  cited. 

The  analysis  of  the  carload  sample  tested  is  as  follows  (for  mine 
samples  see  analyses  28  and  29,  pp.  41-42): 


Analysis  of  carload  sample  of  Lower  Kittanning  coal  from  South  Fork -Mineral  Point 

district. 

Laboratory  No 2152 

Air-drying  loss 2.  90 

Moisture 3.  51 

Volatile  matter 16.  82 

Fixed  carbon 73.  04 

{Ash 6.  63 

'{Sulphur 94 

Hydrogen 4.  56 

Carbon 80.  70 

Nitrogen 1.  26 

Oxygen 5.91 

Calorific  value  determined : 

Calories 7,  933 

British  thermal  units 14,  279 

The  results  of  the  steaming  tests  on  this  coal  are  as  follows : 

Steaming  tests  on  Lower  Kittanning  coal  from  South  Fork- Mineral  Point  district. 


Test  236. 

Test  237. 

Test  238. 

Test  239. 

Test  242. 

Heating  value  of  coal.  .B.  t.  u.  per  pound  of  dry  coal. . 

14,886 

14,868 

14,828 

14,690 

14,659 

Force  of  draft: 

Under  stack  damper 

inch  water. . 

0.43 

0.45 

0.50 

0.63 

0. 47 

Above  fire 

do 

.15 

.16 

.17 

.19 

.16 

Furnace  temnerature 

°F._ 

2,317 

2,266 

2,212 

2,059 

Dry  coal  used  per  square  foot  of  grate  surface  per 

hour 

pounds. . 

15.74 

16.23 

15.69 

17.64 

14.33 

Equivalent  water  evaporated  per 

square  foot  of 

2.93 

water-heating  surface  per  hour. . . 

pounds.. 

2.96 

2.93 

3.08 

2.92 

Percentage  of  rated  horsepower  of  boiler  developed. . . 
Water  apparently  evaporated  per  pound  of  coal  as 

82.0 

83.0 

82.1 

86.5 

81.9 

fired 

pounds.. 

8.51 

8.27 

8.44 

7.98 

8.52 

Water  evaporated  from  and  at  212° 

F.: 

Per  pound  of  coal  as  fired 

do 

10.12 

9.85 

10.05 

9.52 

10. 17 

Per  pound  of  dry  coal 

do 

10.37 

10. 17 

10. 42 

9.75 

10.22 

Per  pound  of  combustible 

do 

11.20 

11.02 

11.29 

10. 71 

11.15 

Efficiency  of  boiler,  including  grate. 
Coal  as  fired: 

percent.. 

67.27 

66.06 

67.86 

64. 10 

67. 19 

Per  indicated  horsepower  hour. 

pounds.. 

2.79 

2.87 

2.81 

2.97 

2.78 

Per  electrical  horsepower  hour. 
Dry  coal: 

do 

3.45 

3.54 

3.47 

3.67 

3. 43 

Per  indicated  horsepower  hour. 

do 

2.73 

2.78 

2. 71 

2.90 

2.77 

Per  electrical  horsepower  hour. , 

do 

3. 37 

3.  43 

3.35 

3.58 

3.41 

Proximate  analysis: 

Moisture 

2. 37 

3.11 

3.56 

2.44 

0.42 

Volatile  matter 

16. 74 

15.68 

16.09 

16. 64 

17.51 

Fixed  carbon 

74.66 

74. 93 

73.85 

73.69 

75.20 

Ash 

6.23 

6.28 

6. 50 

7.23 

6.87 

100.00 

100.00 

100.00 

100.00 

100.00 

SulDhur 

.88 

.89 

.87 

1.12 

1.01 

Bull.  U.  S.  Geol.  Survey  No.  290,  1906,  pp.  178-181. 


72  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Steaming  tests  on  Lower  Kittanning  coal  from  South  Fork- Mineral  Point  district — 

Continued. 


Test  236. 

Test  237. 

Test  238. 

Test  239. 

Test  242. 

Ultimate  analysis: 

Carbon  a 

84. 14 

84.03 

83. 81 

82. 98 

83.35 

Hydrogen  a 

4. 34 

4.35 

4. 33 

4. 28 

4. 15 

Oxygen  o 

2. 93 

2.91 

2.91 

2. 89 

3. 27 

Nitrogen  o 

1.31 

1.31 

1.31 

1.29 

1.32 

Sulphur 

.90 

.92 

.90 

1. 15 

1.01 

Ash 

6. 38 

6.48 

6. 74 

7.41 

6.  90 

100.00 

100. 00 

100.00 

100.00 

100. 00 

a Figured  from  car  sample. 


Test  236:  Size  as  shipped,  run  of  mine.  Size  as  used,  over  1 inch,  6.5  per  cent;  \ inch  to  1 inch,  13.6  per 
cent;  J inch  to  J inch,  22.4  per  cent;  under  -J-  inch,  57.5  per  cent.  Duration  of  test,  9.88  hours.  Kind  of 
grate,  rocking. 

Test  237:  Size  as  shipped,  run  of  mine.  Size  as  used,  over  1 inch,  5.8  per  cent;  £ inch  to  1 inch,  12.3  per 
cent;  \ inch  to  ^ inch,  19.5  per  cent;  under  £ inch,  62.4  per  cent.  Duration  of  test,  10  hours.  Kind  of 
grate,  rocking. 

Test  238:  Size  as  shipped,  run  of  mine.  Size  as  used,  over  1 inch,  5.4  per  cent;  § inch  to  1 inch,  9.1  per 
cent;  J inch  to  £ inch,  14.9  per  cent;  under  \ inch,  70.6  per  cent.  Duration  of  test,  10.02  hours.  Kind  of 
grate,  rocking., 

Test  239:  Size  as  shipped,  run  of  mine.  Size  as  used,  over  1 inch,  4.4  per  cent;  \ inch  to  1 inch,  8.8  per 
cent;  J inch  to  i inch,  16.2  per  cent;  under  £ inch,  70.6  per  cent.  Duration  of  test,  9.92  hours.  Kind  of 
grate,  rocking. 

Test  242:  Size  as  shipped,  run  of  mine.  Size  as  used,  over  1 inch,  2.0  per  cent;  \ inch  to  1 inch,  7.0  per 
cent;  £ inch  to  \ inch,  14.5  per  cent;  under  £ inch,  76.5  per  cent.  Dried  coal.  Duration  of  test,  7.88  hours. 
Kind  of  grate,  plain. 

» 

The  figure  giving  the  number  of  pounds  of  water  evaporated  by 
1 pound  of  dry  coal  from  and  at  a temperature  of  212°  F.  gives  the 
results  of  the  coal  tested  so  far  as  these  relate  to  its  commercial  value, 
and  the  reader  is  referred  to  the  table  on  page  37  for  the  standing 
of  the  Ehrenfeld  coal  among  other  standard  steaming  coals.  The 
results  of  the  tests,  on  the  Ehrenfeld  samples  though  showing  a range 
of  9.75  to  10.42  pounds  of  water  evaporated  per  pound  of  dry  coal 
used,  are  yet,  when  averaged,  among  the  very  best  made  at  the  testing 
plant. 

Coking  tests. — The  coal  from  the  lower  Kittanning  bed  near  South 
Fork  has  been  coked,  and  the  results  of  the  test  on  the  sample  from 
Ehrenfeld  are  given  below : 

Coking  test  on  Lower  Kittanning  coal  from  Ehrenfeld. 

[Run  of  mine;  finely  crushed;  raw;  duration  of  test,  51  hours.] 

Coal  charged pounds. . 10, 000 

Coke  produced do 5,  223 

Breeze  produced do „ 1,  600 


Coke  produced percent..  52.23 

Breeze  produced do 16.  00 


Total  percentage  yield 68.23 

The  product  was  a soft,  dense  coke  of  a dull-gray  color,  in  large  and 
small  chunks.  There  was  a heavy  black  butt  on  the  coke,  and  it  was 
hard  to  burn.  The  cell  structure  was  small. 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


73 


Analyses  of  coal  and  coke. 


Coal. 

Coke. 

Moisture 

3.32 

0. 91 

Volatile  matter 

15.56 

2. 16 

Fixed  carbon 

74. 29 

88.99 

Ash 

6. 83 

7.94 

Sulphur 

1. 12 

.91 

The  yield  of  coke  from  this  test  is  comparatively  high,  but  the  poor 
quality  of  the  coke  shows  that  the  coal  does  not  belong  among  the 
best  coking  coals  of  western  Pennsylvania  and  West  Virginia.  Coke 
made  by  the  Cambria  Steel  Company  with  coal  mined  from  this  bed 
about  Ehrenfeld  proved  well  adapted  to  metallurgical  purposes.  The 
yield  also  was  satisfactory. 

Cupola  tests.a — In  connection  with  the  tests  of  coals  made  at  the 
plant  of  the  United  States  Geological  Survey  at  St.  Louis  in  1904 
practical  melting  tests  were  made  of  coke  that  showed  any  likelihood 
to  be  of  value  to  the  foundry  industry.  Among  those  tested  was  one 
made  from  coal  collected  at  colliery  No.  3 of  the  Pennsylvania,  Beech 
Creek,  and  Eastern  Coal  Company  at  Ehrenfeld.  The  test  was  con- 
ducted in  a 36-inch  foundry  cupola  lent  by  the  Whiting  Foundry 
Equipment  Company,  of  Chicago.  The  36-inch  shell  of  the  cupola  was 
relined  to  26  inches  internal  diameter.  There  were  four  horizontal 
tuyeres  measuring  4 by  6 inches  on  the  outside  and  3 by  13  inches 
on  the  inside  of  the  cupola,  which  were  situated  1 1 inches  above  the 
sand  bottom.  The  total  tuyere  area  was  96  square  inches,  giving  a 
ratio  of  1 to  5.96  with  the  cupola  area.  A No.  6 Sturtevant  fan  run 
at  2,514  revolutions  a minute  furnished  the  blast,  which  was  kept  at 
about  7 ounces. 

The  cupola  test  was  conducted  by  W.  G.  Ireland,  and  the  details  of 
the  method  employed  are  outlined  in  the  references  cited  above  and 
will  not  be  given  here.  The  results  of  the  test  are  shown  in  the  fol- 
lowing table: 


a Prof.  Paper  U.  S.  Geol.  Survey  No.  48,  pt.  3,  1906,  pp.  1367-1370;  Bull.  U.  S.  Geol.  Survey  No.  336, 
1908,  pp.  48,  49,  50,  54,  57,  60,  63. 


Cupola  tests  on  Lower  Kittanning  ( Miller ) coal  from  Ehrenfeld. 


74  MINERAL  RESOURCES  OE  JOHNSTOWN,  PA.,  AND  VICINITY. 


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Cupola  tests  on  Lower  Kittanning  ( Miller ) coal  from  Ehrenfeld— Continued. 


SOUTH  FORK-MINERAL  POINT  DISTRICT.  75 


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76  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Producer-gas  test. — The  following  results  were  obtained  from  the 
producer-gas  test  made  on  the  Ehrenfeld  sample: 


Producer-gas  test  on  Lower  Kittanning  coal  from  Ehrenfeld.a 


- 

Coal  as 
fired. 

Dry 

coal. 

Com- 

busti- 

ble. 

Coal  consumed  in  producer  per  horsepower  per  hour. 

Per  electrical  horsepower: 

Pounds. 

Pounds. 

Pounds. 

Available  for  outside  purposes 

1.25 

1.22 

1.13 

Developed  at  switchboard 

1.18 

1.15 

1.07 

Per  brake  horsepower: 

Available  for  outside  purposes 

1.06 

1.04 

.96 

Developed  at  engine f 

1.00 

.98 

.91 

Equivalent  used  by  producer  plant . 
Per  electrical  horsepower: 

Available  for  outside  purposes 

1.35 

1.32 

1.22 

Developed  at  switchboard 

1.28 

1.25 

1.15 

Per  brake  horsepower: 

Available  for  outside  purposes 

1.15 

1.12 

1.04 

Developed  at  engine 

1.09 

1.06 

.98 

a Bull.  U.  S.  Geol.  Survey  No.  290,  1906,  pp.  180-181. 


Size  asshipped,  run  of  mine;  size  as  used,  not  determined.  Duration,  50  hours. 
Average  electrical  horsepower,  187.9;  average  British  thermal  units  gas  per  cubic 
foot,  133;  total  coal  fired,  11,100  pounds. 


Analyses. 


Coal. 

Gas  by  volume. 

Moisture 

2.49 

Carbon  dioxide  (CO2) 

9.9 

Volatile  matter 

16. 61 

Carbon  monoxide  (CO) 

18.7 

Fixed  carbon 

73.  70 

Hydrogen  m2) 

14.1 

Ash 

7.20 

Methane  (CH<) 

2.2 

100. 00 

Nitrogen  (N2) 

55.1 

Sulphur 

.91 

100.0 

Occurrence  and  'physical  character. — The  Lower  Kittanning  coal 
near  South  Fork  (see  fig.  12)  has  a section  similar  to  that  of  the  bed 
near  Johnstown,  already  described.  Its  main  bench,  however,  is 
thicker,  averaging  nearly  4 feet  and  in  some  places  reaching  5 feet, 
with  no  partings.  The  double  structure — that  is,  the  occurrence 
of  a main  bench  with  the  under  coal — which  is  fairly  persistent  in 
the  Johnstown  district,  is  even  more  apparent  about  South  Fork. 
Some  of  the  mines,  however,  show  it  only  here  and  there.  In  other 
physical  aspects  this  coal  resembles  the  Lower  Kittanning  bed  about 
Johnstown.  Its  roof  of  dense  shale  or  sandstone,  the  general  absence 
of  “draw  slate”  or  of  clay  veins,  and  the  irregular  floor  are  all  com- 
mon to  the  bed  in  both  districts.  The  top  few  inches  of  the  coal 
is  usually  bony  and  has  to  be  discarded.  In  appearance  the  coal  is 
lustrous  and  much  of  it  is  iridescent,  and  its  columnar  cleavage  is 
one  of  its  more  characteristic  features. 


SOUTH  FORK-MINERAL  POINT  DISTRICT. 


77 


The  lower  bench  varies  in  thickness,  but  is  in  places  as  much  as 
2 feet  thick;  this  thickness  is  reached  near  both  South  Fork  and 
Mineral  Point.  The  lower  coal  is  underlain  by  valuable  plastic 
clay  and  is  separated  from  the  main  bench  by  a few  inches  to  a foot 
of  clay  or  shale.  So  far  as  known,  the  under  coal  is  not  utilized. 
As  a rule  it  is  not  so  persistent  along  the  southeastern  margin  of  the 
Wilmore  Basin  if  the  sections  obtained  by  Mr.  Butts  and  Mr.  Phalen 


Figure  12.— Sections  of  Lower  Kittanning  (Miller  or  B)  coal  in  the  South  Fork-Mineral  Point  district. 

Scale,  1 inch=5  feet. 

1.  Keystone  Coal  and  Coke  Company,  Argyle  No.  2,  South  Fork. 

2.  Keystone  Coal  and  Coke  Company,  Argyle  No.  1,  South  Fork. 

3.  Priscilla  Coal  Company,  South  Fork. 

4.  Pennsylvania,  Beech  Creek  and  Eastern  Coal  Company,  Ehrenfeld. 

5.  Stineman  Coal  and  Coke  Company,  No.  2,  South  Fork. 

6.  Stineman  Coal  and  Coke  Company,  No.  4,  South  Fork. 

7.  Stineman  Coal  Mining  Company,  No.  1,  South  Fork. 

8.  Stineman  Coal  and  Coke  Company,  No.  2,  Timber  opening,  South  Fork. 

9.  South  Fork  Coal  Mining  Company,  No.  1,  South  Fork. 

10.  Valley  Smokeless,  No.  3,  Mineral  Point. 

11.  Page  & Reighard,  Juniper  mine,  Mineral  Point. 

12.  George  Schafer,  Mineral  Point. 


in  1903  are  representative.  It  here  appears  locally,  as  the  following 
section  shows: 


Section  of  Lower  Kittanning  ( Miller ) coal  at  Henriette  shaft  No.  1,  Llanfair,  Pa. 

Ft.  in. 

3 9 

3 

11 

LOWER  ALLEGHENY  COALS. 

A coal  65  feet  below  the  Lower  Kittanning  (Miller)  bed  has  been 
opened  at  a few  points  about  South  Fork  and  Mineral  Point.  This 
coal  probably  corresponds  to  the  Brookville  or  A coal.  Most  of  the 
openings  have  fallen  shut,  but  one  bank  is  mined  at  South  Fork  to 
supply  the  local  brick  company.  The  coal  is  better  known  locally 
as  the  Dirty  A or  Six-foot  coal,  but  where  measured  (see  fig.  13) 
only  3J  feet  of  coal  was  observed.  The  bone  parting  observed  a 


Coal. 

Slate. 

Coal. 

Clay. 


78  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


foot  from  the  base  is  only  an  inch  thick.  The  roof  is  shale  or  sand- 
stone and  so  far  as  known  gives  no  trouble.  The  coal  runs  as  thick 
as  5 feet  and  as  thin  as  3 feet.  According  to  reports,  4 feet  may  be 
considered  an  average.  The  coal  is  reported  not  to  be  roily  and  no 
clay  veins  of  importance  have  been  encountered. 

It  has  a composition  indicated  by  analysis  36, 
page  41.  From  the  high  ash  and  sulphur  content, 
aggregating  more  than  15  per  cent,  the  coal  deserves 
the  name  Dirty  A,  which  is  often  applied  to  it.  In 
other  respects  the  analysis  corresponds  with  those 
of  other  coals  of  the  area,  being  relatively  high  in 
figure  13.— Section  of  fixed  carbon  and  low  in  volatile  matter.  It  is  pos- 
the  Brookviiie  (A)  coal  sible  that  the  coal  may  be  valuable  in  this  district, 
wickes,  south  Fork,  but  the  tact  that  it  has  not  been  developed  on  an 
scale,  1 inch=5  feet.  extensive  scale  and  apparently  has  not  come  into 

competition  with  the  other  coals  of  the  district  is  strong  presumptive 
evidence  that  in  quality  it  is  not  up  to  the  standard  of  the  other  coals 
mined  about  South  Fork. 

POTTSVILLE  COALS. 

But  one  other  coal  in  the  South  Fork-Mineral  Point  district  deserves 
brief  attention.  This  is  the  coal  associated  with  the  flint  clay  (see 
pp.  121-123)  at  the  Mercer  horizon.  The  coal  is  not  worked  and 
where  observed  was  merely  a thin  streak  in  the  middle  of  the  clay. 
The  following  section  was  seen  and  measured  at  the  clay  mine  of 
J.  H.  Wickes: 

Section  of  clay  and  coal  at  Mercer  horizon , South  Fork. 

Roof,  heavy  sandstone 

Plastic  clay 

Coal 

Flint  clay 

Sandstone. 

Though  the  coal  is  not  workable  here,  it  is  quite  possible  that  it 
may  be  of  workable  thickness  locally.  In  this  district,  however,  it 
can  not  be  regarded  as  among  the  commercial  beds  of  the  future. 

BLACKLICK  CREEK  DISTRICT. 

EXTENT. 

In  the  Blackliok  Creek  district  will  be  included  the  coal  occurrences 
along  Blacklick  Creek  and  its  South  Branch.  Operations  on  these 
coals  are  confined  almost  exclusively  to  the  creek  valley,  the  principal 
mining  towns  being  Nanty  Glo,  Cardiff,  Twin  Rocks,  Weber,  Vinton- 
dale,  and  Wehrum.  The  coals  outcrop  from  Nanty  Glo,  where  they 
are  brought  above  drainage  level  on  the  east  margin  of  the  Laurel 


Ft.  in. 

31 

*-2 

41 


BLACKLICK  CREEK  DISTRICT. 


79 


Ridge  anticline,  westward  to  Yintondale,  on  the  west  flank  of  the 
same  anticline.  Just  west  of  Yintondale  the  highest  workable  coal 
disappears  below  drainage  level,  and  still  farther  west,  at  Wehrum, 
mining  operations  are  conducted  by  means  of  a shaft.  West  of 
Wehrum  the  coal-bearing  beds  are  brought  above  drainage  level 
just  at  the  western  edge  of  the  quadrangle,  near  Dilltown.  A few 
country  banks  have  also  been  opened  on  Mardis  Run. 


GEOLOGIC  POSITION  OF  COALS. 

Figure  2 shows  the  relations  between  the  principal  coals  in  the 
Blacklick  Creek  district,  and  the  following  section,  measured  along 
the  railroad  and  in  the  hills  north  of  Yintondale,  shows  the  character 
of  the  beds  which  make  up  the  intervals: 


Section  north  of  Vintondale. 


Ft. 


Sand  and  shale 9 

Coal,  reported  42  inches,  thinning  to  18  inches  when  run  in 
from  the  outcrop  (D  coal). 

Concealed : 57 

Sandstone 15 

Concealed 10! 

Shale,  sandy 5 

Concealed 10! 

Shales,  brown-drab 10 

Coal,  2 feet  3 inches..  1 

Clay,  1 inch >Middle  Kittanning  (C)  coal 2 

Coal,  6J  inches J 

Shales 7 

Chiefly  clay 5 

Sandstone 3 

Shale,  black 2 

Sandstone  with  black  shale  partings 5 

Shale,  sandy,  becoming  concretionary  and  ferruginous  at  base.  20 

Interval 4 

Shale,  variegated  black  and  drab 6 

Coal,  3 feet  8 inches. 

Shale,  2 inches 

Coal,  4 inches 

Clay,  2 inches 

Coal,  9 inches 

Shales,  sandy 

Fire  clay,  dark  gray 3 

Sandstone,  drab,  resembling  ganister 

Clay,  light  drab 3 


Lower  Kittanning  (B  or  Miller)  coal 5 


in. 


io§ 

8 

2 

1 

4 

2 

8 


1 


6 

5 

2-3 


The  Middle  Kittanning  (C)  coal,  the  first  above  the  Lower  Kittan- 
ning (Miller  or  B)  bed,  which  is  the  coal  worked  along  Blacklick 
Creek,  occurs  at  an  interval  above  it  of  about  50  feet.  This  coal  is 
nearer  the  Lower  Kittanning  at  Nanty  Glo,  having  been  reported  only 
34  feet  above  it  near  the  opening  of  the  Ivory  Hill  Mining  Company 
at  that  place.  At  Big  Bend  its  interval  above  the  Lower  Kittanning 
is  about  45  feet. 


80  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

There  is  still  another  coal  at  the  top  of  the  section  deserving 
attention.  At  Yintondale  a gully  was  dug  up  the  hill  from  railroad 
level  where  the  Lower  Kittanning  coal  outcrops.  The  section  given 
above,  except  the  part  between  the  Lower  and  Middle  Kittanning 
coals,  was  measured  in  this  gully.  The  top  coal  was  observed  by 
hand  level  to  be  108  feet  above  the  intermediate  (Middle  Kittanning 
or  C)  coal,  and  the  interval  between  the  Lower  and  Middle  Kittan- 
ning beds  was  found  to  be  46J  feet.  Thus  from  the  top  coal  to  the 
Lower  Kittanning  (B)  bed  the  distance  is  about  164  feet.  At  Nanty 
Glo  a workable  coal  (probably  the  Lower  Freeport  or  D coal)  was 
observed  by  hand-level  measurement  to  occur  150  feet  above  the 
Lower  Kittanning  coal,  and  at  Twin  Rocks  a coal  was  reported  at 
almost  exactly  the  same  interval  by  the  engineer  of  the  Big  Bend 
collieries.  At  Welirum  certain  of  the  diamond-drill  records  show  a 
coal  about  the  same  interval  above  the  Lower  Kittanning  coal.  So 
far  as  the  writers  are  aware,  this  is  the  highest  coal  of  any  impor- 
tance in  the  Blacklick  Creek  district.  About  50  feet  above  it  occurs 
an  unworkable  small  coal,  which  is  regarded  as  the  equivalent  of 
the  Upper  Freeport  or  E bed.  The  highest  workable  coal  along 
Blacklick  Creek  will  therefore  be  regarded  tentatively  as  the  Lov^er 
Freeport  (D)  coal. 

The  nomenclature  of  the  coals  discovered  in  the  Blacklick  Creek 
district  and  the  intervals  between  them  have  been  graphically  given 
by  DTnvilliers.®  Fie  places  the  first  coal  above  the  Lower  Kittanning 
(B)  at  60  feet  above  it,  but  the  hand-leveled  sections  at  Vintondale, 
as  well  as  measurements  made  at  Twin  Rocks  and  reports  from 
authorities  at  Nanty  Glo,  make  this  coal  at  least  15  feet  lower,  and 
instead  of  lettering  it  C',  as  DTnvilliers  has  done,  the  writers  prefer 
to  regard  it  as  the  C coal  and  the  representative  of  the  Middle  and 
not  the  Upper  Kittanning  bed.  Further,  DTnvilliers  places  the 
next  higher  coal  at  1 20  feet  above  the  Lower  Kittanning  (B)  and  the 
next  at  approximately  60  feet  higher.  This  bed,  which  he  denotes 
as  the  E with  a question,  he  describes  as  a “good  bed,  thinning 
westward  to  about  3 feet.”  It  is  believed  that  this  is  the  coal 
measured  at  Nanty  Glo,  at  Twin  Rocks,  near  Rexis,  and  on  Mardis 
Run,  though  the  interval  obtained  (150  to  160  feet  above  the  Lower 
Kittanning  bed)  falls  short  by  at  least  20  feet  of  the  interval  platted 
by  DTnvilliers. 

ALLEGHENY  COALS. 

LOWER  FREEPORT  (d)  COAL. 

Name  and  'position . — Some  question  arises  as  to  whether  the 
highest  workable  coal  in  the  Allegheny  formation  is  the  Upper  or 
Lower  Freeport.  It  is  quite  certain  that  the  full  complement  of 
coals  in  the  formation  is  not  developed  along  Blacklick  Creek,  at 


a Summary  Final  Rept.  Geol.  Survey  Pennsylvania,  1895,  pi.  415,  p.  2222. 


BLACKLICK  CREEK  DISTRICT. 


81 


least  not  as  clearly  as  in  the  Johnstown  Basin.  Only  three  workable 
coals  in  the  Allegheny  (above  and  including  the  B bed)  were  deter- 
mined with  any  certainty,  and,  though  more  may  be  present,  they 
must  be  small  and  hence  of  no  value  except  for  stratigraphic  purposes. 

The  position  of  the  highest  workable  coal  is  very  definitely  fixed. 
At  Nanty  Glo  it  is  just  150  feet  by  hand  level  above  the  Lower  Kittan- 
ning (B)  bed.  On  the  Selderville  road,  between  Nanty  Glo  and  Twin 
Rocks,  the  interval,  measured  by  barometer,  is  1 58  feet ; at  Yintondale, 
by  hand  level,  it  was  made  164  feet;  and,  as  stated  by  the  engineer 
gf  the  Big  Bend  collieries,  the  interval  at  Big  Bend  is  about  150  feet. 
There  is  a question  as  to  whether  this  coal  is  the  Upper  Freeport  or 
the  Lower  Freeport,  and  this  question  the  writers  are  unable  to  settle 
definitely.  Objection  should  not  be  made  to  its  being  considered  as 
the  Upper  Freeport  on  the  basis  of  its  small  interval  above  the  Lower 
Kittanning  coal,  as  this  interval  is  even  less  than  150  feet  at  New 
Germany.  In  this  report,  however,  it  will  be  regarded  as  the  Lower 
Freeport  coal. 

Extent  and  development. — The  Lower  Freeport  (D)  coal  has  been 
opened  by  the  Ivory  Hill  Coal  Mining  Company  east  of  Nanty  Glo 
and  on  the  side  of  the  hill  just  west  of  the  No.  14  colliery  of  the 
Pennsylvania,  Beech  Creek,  and  Eastern  Coal  Company.  It  has 
been  prospected  and  its  position  and  character  are  well  known  at 
Twin  Rocks  and  to  the  northeast,  opposite  No.  2 colliery  of  the  Big 
Bend  Coal  Mining  Company.  About  Yintondale  it  has  been  pros- 
pected and  its  character  is  known,  as  a section  of  the  coal  near 
Rexis  was  measured  by  Mr.  Martin.  On  Mardis  Run,  just  off  the 
northwest  corner  of  the  Johnstown  quadrangle,  the  coal  is  opened 
and  a section  was  measured.  At  present  it  is  not  a commercial  factor 
in  the  Blacklick  Creek  district,  but  it  can  be  classed  among  the  future 
commercial  coals  of  this  district. 

Occurrence  and  physical  character. — Figure  14  shows  the  mode  of 
occurrence  of  the  Lower  Freeport  coal.  It  generally  consists  of  two 

1 2 3 4. 

1 


Figure  14.— Sections  of  the  Lower  Freeport  (D)  coal  along  Blacklick  Creek.  Scale,  1 inch  = 5 feet. 

1,  Mardis  Run  near  northwest  edge  of  Johnstown  quadrangle;  2,  Blacklick  Creek  near  Rexis;  3,  road 
south  of  Twin  Rocks;  4,  Twin  Rocks;  5,  Ivory  Hill  Coal  Mining  Company,  Nanty  Glo. 

or  three  benches  separated  by  thin  bone  partings,  the  coal  aggre- 
gating from  3 to  3J  feet  in  thickness.  At  Yintondale,  Twin  Rocks, 
69516°— Bull.  447—11 6 


82  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

and  Nanty  Glo  the  upper  bench  varies  from  1J  to  nearly  2 feet  in 
thickness,  and  the  lower  bench  averages  about  15  inches,  with  some 
few  inches  of  bone  beneath.  At  Twin  Rocks  this  is  underlain  by  a few 
inches  of  coal.  On  Mardis  Run  the  coal  is  more  broken,  consisting 
of  three  benches,  each  about  a foot  thick.  The  roof  is  usually  shale 
and  the  coal  is  underlain  by  clay.  The  presence  of  the  parting  in 
this  coal  has  been  a drawback  to  operations  on  it,  but  it  is  quite  prob- 
able that  it  will  yet  be  worked;  in  fact,  it  was  worked  during  the  hard- 
coal  famine  of  1902-3  and  gave  satisfaction.  If  proper  care  is  exer- 
cised in  separating  the  bony  parting,  it  should  be  readily  marketed. 
The  resemblance  of  the  sections  to  those  of  the  Upper  Freeport  coal 
near  South  Fork  is  marked. 

MIDDLE  KITTANNING  COAL. 

A little  more  than  100  feet  below  the  Upper  Freeport  coal  and  from 
35  to  45  feet  above  the  main  coal  of  the  Blacklick  district  (Lower 
Kittanning  or  Miller  bed)  occurs  a coal  which  is  persistent  along  South 
Branch  of  Blacklick  Creek.  It  has  been  observed  at  Twin  Rocks, 
Nanty  Glo,  and  Vintondale,  and  its  interval  with  respect  to  the  main 
Blacklick  coal  has  been  measured  at  the  two  last-named  places.  It 
has  been  called  the  Middle  Kittanning  coal  because  it  is  the  first  coal 
above  the  Lower  Kittanning  bed.  At  Vintondale  the  following  sec- 
tion was  measured : 

Section  of  Middle  Kittanning  coal  at  Vintondale. 


Shale  roof.  Ft.  in. 

Coal 2 3 

Clay 1 

Coal 6| 

Clay. 


The  coal  here  has  a thickness  of  33 \ inches  and  is  therefore  workable. 
Owing  to  its  persistence,  it  may  be  regarded  as  among  the  coals  that 
will  in  the  future  be  worked  in  this  region,  though  it  may  be  some  time 
before  it  will  be  necessary  to  draw  on  this  coal  as  a source  of  supply. 

LOWER  KITTANNING  (b)  COAL. 

N ante  and  'position . — The  main  coal  of  the  Blacklick  district  is  con- 
sidered the  Lower  Kittanning  (Miller  or  B)  coal  and  corresponds  to 
this  coal  about  South  Fork.  Some  question  has  been  raised  as  to  this 
correlation  and  the  coal  has  been  regarded  as  the  equivalent  of  the 
Upper  Kittanning  or  C'  coal.  The  objections  to  the  latter  view  have 
been  summed  up  by  DTnvilliers®  in  the  following  words,  with  which 
the  writers  are  in  full  agreement. 

The  whole  character  of  the  “Blacklick  seam”  is  totally  unlike  the  appearance  of 
the  Kittanning  upper  bed(C/)  as  exposed  anywhere  in  Clearfield,  Cambria,  or  Somerset 
counties.  On  the  other  hand,  its  double  structure,  columnar  cleavage,  partings,  roof 


a Summary  Final  Rept.  Geol.  Survey  Pennsylvania,  1895,  p.  2222. 


BLACKLICK  CREEK  DISTRICT. 


83 


and  floor,  and  excellent  chemical  character  most  strongly  resemble  the  features  of  the 
Kittanning  lower  bed  (B  or  Miller  seam),  all  through  southern  Cambria  and  especially 
in  the  Paint  and  Shade  Creek  valleys  of  Somerset  County.  * * * At  no  place  in 
the  Blacklick  region  has  the  cement  bed  been  noticed  beneath  this  coal,  which  would 
identify  it  as  bed  C'. 

Extent  and  development. — This  coal  is  often  referred  to  as  the  Black- 
lick Creek  seam.  It  appears  above  drainage  level  just  east  of  Nanty 
Glo,  on  South  Branch  of  Blacklick  Creek,  where  it  has  been  opened  by 
the  Ivory  Hill  Coal  Mining  Company.  In  the  southern  part  of  Nanty 
Glo  are  two  important  mines  on  this  coal — the  Pennsylvania,  Beech 
Creek,  and  Eastern  Coal  Company’s  colliery  No.  14  and  that  of  the 
Nanty  Glo  Coal  Mining  Company.  Some  distance  north  of  the  town 
is  the  mine  of  the  Lincoln  Coal  Company,  and  still  farther  north,  near 
the  edge  of  the  quadrangle,  is  the  opening  of  the  Cardiff  Coal  Company. 
The  next  mining  center  to  the  west  is  Twin  Rocks  or  Expedit  post- 
office,  near  which  are  located  collieries  Nos.  1 and  2 of  the  Big  Bend 
Coal  Mining  Company  and  colliery  No.  3 of  the  Commercial  Coal 
Mining  Company.  Colliery  No.  4 of  the  latter  company  is  located 
about  4 miles  farther  west,  at  a little  settlement  called  Weber.  The 
Vinton  Colliery  Company  controls  the  workings  on  this  bed  about 
Vintondale.  Four  out  of  its  five  collieries  were  active  in  the  summer 
of  1906  and  colliery  No.  6 was  just  being  opened.  The  coal  goes  below 
drainage  level  in  the  town  and  the  operations  to  the  west  at  Wehrum 
are  conducted  by  shafting  for  the  coal  to  a depth  of  187  feet.  On  the 
west  side  of  the  Barnesboro  or  Westover  Basin  the  bed  appears  above 
drainage  level  just  at  the  edge  of  the  quadrangle  and  has  been  worked 
in  a small  way  by  Id.  R.  Dill  about  a mile  northwest  of  Dilltown.  The 
development  of  this  coal  along  Blacklick  Creek  is  of  recent  date,  and 
the  production  of  this  district,  which  was  only  5,000  tons  in  1894,  had 
increased  in  1905  to  1,045,802  tons,  valued  at  $1,019,617. 

Chemical  character. — The  composition  of  this  coal  is  indicated  by 
analyses  17  to  27  (pp.  40-41).  This  exceptionally  complete  series  of 
analyses  shows  that  the  Lower  Kittanning  (Miller)  coal  has  much  the 
same  character  along  Blacklick  Creek  as  at  Johnstown  and  South  Fork. 
The  moisture  in  the  coal  is  low,  in  no  sample  exceeding  4 per  cent. 
The  volatile  matter  is  likewise  low  and  remarkably  uniform,  ranging 
from  more  than  17  per  cent  to  less  than  19  per  cent.  Fixed  carbon 
ranges  from  67  to  73  per  cent — a slight  range  considering  that  the 
samples  were  obtained  by  three  individuals  from  scattered  mines. 
Ash  is  on  the  whole  low,  but  sulphur  is  rather  high,  in  one  sample 
exceeding  4 J per  cent.  As  a whole,  however,  the  figures  all  point  to  a 
high-grade  coal. 

Steaming  tests. — Steaming  tests  have  been  made  on  Lower  Kittan- 
ning coal  collected  at  Wehrum  by  the  United  States  Geological 
Survey.®  The  analyses  on  the  samples  used  are  as  follows: 


a Bull.  U.  S.  Geol.  Survey  No.  332, 1908,  pp.  201-202. 


84  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Chefnical  analyses  of  Lower  Kittanning  coals  from  Wehrum.a 


Test  472. 

Test  473. 

Test  467. 

(Moisture 

1.88 

2.45 

3.90 

23.35 

64.65 

Volatile  matter 

17.60 

17. 55 

8' 

Fixed  carbon 

69. 06 

70.56 

Ph 

/Ash 

11.46 

9.44 

8. 10 

[\Sulphur 

5.37 

3. 87 

3. 11 

Hydrogen : 

4. 13 

4.31 

4.35 

Carbon 

75.63 

78.83 

78.71 

Nitrogen 

1. 15 

1.21 

1.09 

Oxygen 

1.94 

2.00 

4. 18 

Ash 

11.68 

9. 68 

8.  43 

Sulphur 

5.47 

3. 97 

3.24 

a Proximate  analysis  of  fuel  as  fired;  ultimate  analysis  of  dry  fuel  figured  from  car  sample.  (See  analyses 
10  and  11,  pp.  40-41.) 


The  results  of  the  steaming  tests  are  as* follows: 

Steaming  tests  on  Lower  Kittanning  coal  from  Wehrum. 


Test  472.  a 

Test  473.o 

Test  467. 

Size  as  used: 

Over  1 inch 

per  cent. . 

8.2 

4.6 

^ inch  to  1 inch  . . 

. .do 

11. 1 

6.9 

a inch  to  ^ inch 

do 

19.2 

13.9 

Under  j inch. 

. . .do. . . 

61.5 

74.6 

Average  diameter 

. . .inch. . 

0.41 

0.31 

Duration  of  test 

hours. . 

8.  75 

9. 77 

8. 87 

Heating  value  of  fuel B.  t.  u.  per  pound  of  dry  fuel. . 

13,729 

14,240 

14,258 

Force  of  draft: 

Under  stack  damper 

..inch  of  water.. 

0. 81 

0.82 

0. 76 

Above  fire 

do 

.27 

.23 

.17 

Furnace  temperature 

Dry  fuel  used  per  square  foot  of  grate  surface  per  hour. . . 

°F. . 

2,512 

2,615 

2,753 

pounds.. 

16.87 

17.24 

17.63 

Equivalent  water  evaporated  per  square  foot  of  water-heating  surface  per 
hour pounds.. 

3.00 

3.25 

3.53 

Percentage  of  rated  horsepower  of  boiler  developed 

84.2 

91.2 

99.00 

Water  apparently  evaporated  per  pound  of  fuel  as  fired. . 
Water  evaporated  from  and  at  212°  F.: 

pounds. . 

7.27 

7.65 

7.98 

Per  pound  of  fuel  as  fired 

do 

8.76 

9.22 

9.65 

Per  pound  of  dry  fuel 

do 

8.93 

9.45 

10. 04 

Per  pound  of  combustible 

do 

10.57 

10.85 

11.30 

Efficiency  of  boiler,  including  grate 

per  cent. . 

62.81 

64.09 

68.00 

Fuel  as  fired: 

Per  indicated  horsepower  hour 

pounds. . 

3.23 

3.07 

2. 93 

Per  electrical  horsepower  hour 

Dry  fuel: 

Per  indicated  horsepower  hour 

do 

3.99 

3. 79 

3.62 

do 

3. 17 

2. 99 

2.82 

Per  electrical  horsepower  hour 

do 

3.91 

3.69 

3.48 

a Run  of  mine. 


Test  467  made  on  Renfro  w briquets  from  briquetting  test  176  (p. 
87),  which  burned  freely  with  short  flame,  5.4  per  cent  black  smoke, 
and  very  hot  fire;  briquets  coking  well  and  throwing  off  fragments  of 
coke  in  ash  during  combustion;  39  per  cent  clinker,  thin,  metallic, 
red  and  black,  brittle  when  cold;  ash  of  dark-gray  color,  looked  like 
coke. 

The  figures  giving  the  pounds  of  water  evaporated  from  and  at  a 
temperature  of  212°  F.  per  pound  of  dry  fuel  used  represent  the 
value  of  the  coal  for  steaming.  The  first  two  tests  give  8.93  and 
9.45,  or  an  average  of  9.19,  which  compares  very  well  with  10.545, 
the  figure  for  the  first-class  steaming  coal  from  Fayette,  W.  Va.  (See 


BLACKLICK  CREEK  DISTRICT. 


85 


p.  37.)  The  figure  for  test  467  (10.04)  represents  the  steaming  value 
of  briquets  and  strictly  speaking  should  not  be  used  in  making  com- 
parisons with  the  results  obtained  from  the  raw  coal. 

Coking  tests. — The  results  of  the  coking  tests  made  on  this  coal  are 
given  below.  ° 


Coking  tests  on  Lower  Kittanning  coal  from  Wehrum. 

[Run  of  mine,  washed.] 

Test  185. 

Test  188. 

Sizfi  as  used  . 

Finely 
crushed. 
61 
9,750 
5,779 
59. 27 
262 
2.69 
61.96 

Run  of 

Duration  of  test. . 
Coal  charged 

Coke  produced 

Breeze  produced . . 
Total  yield 

hours. . 

pounds . . 

/ do 

\per  cent. . 

1 pounds... 

\per  cent. . 

do 

mine. 

54 
12,460 
8,144 
65.36 
332 
2.  66 
68.02 

Analyses  of  coal  and  coke. 


• 

Test  185. 

Test  188. 

Coal. 

Coke. 

Coal. 

Coke. 

Moisture 

7.19 
17.86 
69.57 
5.  38 
1.  63 

0. 56 
.32 

91. 10 
8.02 

1.  46 

4.53 

18.56 

70.63 

6.28 

1.85 

0.  57 
.55 
90.  23 
8.  65 
1.54 

Volatile  matter 

Fixed  carbon 

Ash 

Sulphur 

The  coke  resulting  from  the  first  test  was  of  a dull-gray  color, 
soft  and  dense,  with  high  sulphur.  The  second  test,  with  run-of- 
mine  coal,  produced  a light-gray  silvery  coke,  much  better  than  the 
coke  from  the  finely  ground  coal.  In  the  coke  from  the  second 
test,  also,  the  sulphur  is  high.  The  yield  in  the  second  test  was  much 
better  than  that  in  the  first.  The  coal  mined  at  Nanty  Glo  from  this 
bed  has  been  tested  in  beehive  ovens  at  Gallitzin.  It  produced 
coke  of  good  structure  but  of  dull  appearance.  As  in  the  Wehrum 
samples,  an  insufficient  amount  of  sulphur  was  volatilized.  The 
Lackawanna  Coal  and  Coke  Company  has  experimented  with  its  coal 
about  Wehrum,  but  the  washeries  have  long  been  closed  and  the 
results  of  the  coking  tests  could  not  be  learned.  The  Vinton  Colliery 
Company  has  recently  built  a large  by-product  plant  at  Vintondale 
and  a large  part  of  the  coal  mined  from  colliery  No.  6 in  1907  was 
coked  in  it. 


a Bull.  U.  S.  Geol.  Survey  No.  332, 1908,  p.  203. 


86  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Producer-gas  test. — The  following  producer-gas  test  was  made: 

Producer-gas  test  on  Lower  Kittanning  coal  from  Wehrum.a 


Coal  as 
fired. 

Dry  coal. 

Combus- 

tible. 

Coal  consumed  in  producer  per  horsepower  per  hour. 

Per  electrical  horsepower: 

Pounds. 

Pounds. 

Pounds. 

Commercially  available 

1. 29 

1. 26 

1. 12 

Developed  at  switchboard 

1.  24 

1. 21 

1.08 

Per  brake  horsepower: 

Commercially  available 

1. 10 

1.  07 

.96 

Developed  at  engine 

1.  05 

1.03. 

.92 

Equivalent  used  by  producer  plant. 
Per  electrical  horsepower: 

Commercially  available 

1.43 

1.  39 

1.25 

Developed  at  switchboard 

1.  37 

1.  34 

1.20 

Per  brake  horsepower: 

Commercially  available 

1.22 

1.18 

1.  06 

Developed  at  engine 

1. 17 

1. 14 

1.02 

a Lump  coni.— Size  as  used:  Over  1 inch,  7 per  cent;  \ inch  to  1 inch,  14  per  cent;  \ inch  to  \ inch,  18  per 
cent;  under  \ inch,  61  per  cent.  Duration  of  test,  24  hours.  Average  electrical  horsepower,  191.8.  Average 
B.  t.  u.  per  cubic  foot  of  gas,  144.4.  Total  coal  fired,  5,700  pounds. 


Analysis  of  gas  by  volumes 


Carbon  dioxide  (C02) 10.  7 

Carbon  monoxide  (CO) 17.  2 

Hydrogen  (H2) 1&.  8 

Methane  (CH4) 2.  2 

Nitrogen  (N2) 53.8 

Ethylene  (C2H4) 3 


Washing  tests. — Washing  tests  were  made  as  follows.  The  figures 
indicate  that  finer  crushing  is  advantageous.  The  loss  of  “good 
coal  ” (by  which  is  meant  all  coal  of  a quality  equal  to  or  better  than 
that  of  the  washed  coal)  in  the  refuse  will  not  exceed  2 per  cent. 


Float  and  sink  tests  of  Lower  Kittanning  coal  from  Wehrum. 


Percentage 
of  float. 

Analysis. 

Number  of  test. 

Size 

used 

Specific 
gravity  of 
solution 
used. 

Sink 

(per 

Ash. 

Sulphur. 

(inch). 

To 

refuse. 

To 

total 

sample. 

cent) . 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

On  raw  coal  (preliminary); 
1 

h 

i 

1.35 

72 

28 

5:  47 

44 

1.30 

66 

2 

1.  41 

78 

22 

5.27 

46 

1.  45 

62 

3 

i 

h 

1.  45 

80 

20 

5.54 

43 

1.  54 

59 

4 

1.  52 

81 

19 

6.26 

36 

1.  71 

55 

On  refuse  (float):  b 
1 

1.  35 

11.  80 

2.95 

4.  95 

1.71 

2 

1.  41 

13.  20 

3.  30 

6.50 

2. 13 

3 

1.  46 

14  50 

3.  64 

7.65 

2.29 

4 

1.51 

17.20 

4.  30 

8.15 

2.88 

a For  analyses  of  fuel  used  see  analysis  27,  p.  41. 

b Duration  of  test,  2 hours.  Size  as  used,  through  1-inch  screen.  Jig  used,  special;  speed,  70  revolutions 
per  minute;  stroke,  2\  inches.  Raw  coal,  20.37  tons;  washed  coal,  15.25  tons,  or  75  per  cent;  refuse,  5.12 
tons,  or  25  per  cent. 


BLACKLICK  CREEK  DISTRICT. 


87 


Analyses. 


Sample  tested. 

Moist- 

ure. 

Ash. 

Sulphur. 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

Per 

cent. 

3.  77 
1.  53 
19.  78 

Per 

cent 

reduc- 

tion. 

Raw  coal,  car  sample 

3.13 
6.  45 
5.78 

9.81 
5.  38 
47. 18 

Washed  coal 

45 

59 

Refuse 

Briquetting  tests. — Two  briquetting  tests  were  made  of  the  coal. 
Test  176,  with  7 per  cent  binder  (water-gas  pitch),  gave  satisfactory 
briquets,  which  were  tough  and  easily  handled  without  breaking 
when  warm,  but  which  were  brittle  when  cold;  they  broke  with 
characteristic  smooth,  glossy  fracture,  hard  surface,  and  sharp  edges. 
In  test  184  the  Wehrum  coal  was  mixed  with  an  approximately 
equal  portion  of  anthracite  graphitic  coal  from  Cranston,  near  Provi- 
dence, R.  I.  From  this  mixture  excellent  briquets  were  made  with 
6.25  per  cent  binder  on  the  Renfrow  (American)  machine.  Although 
the  pitch  used  had  a low  melting  point,  the  briquets  handled  well 
from  the  machine  and  piled  without  stocking.  The  outer  surface 
was  very  hard  and  smooth  and  broke  without  crumbling,  giving  a 
smooth  fracture  and  sharp  edges. 

Briquetting  tests  of  coal  frtim  Wehrum. 

[Water-gas  pitch  binder.] 


Test  Test 
176.a  184.6 


Test  Test 

176.  184. 


Details  of  manufacture: 

Machine  used 

Temperature  of  briquets. . °F. . 
Binder — 

Laboratory  No 

Amount .per  cent. . 

Weight  of — 

Fuel  briquetted . .pounds. . 

Briquets,  average do 

Heat  value  per  pound — 


Fuel  as  received.. B.  t.  u.. 

Fuel  as  fired do 

Binder do 

Drop  test  (1-inch  screen): 

Held per  cent. . 

Passed do 


Renf. 

Renf. 

185 

185 

4553 

4543 

7 

6. 25 

8,000 

10, 000 

0.  420 

0.5 

13, 712-j 

cl3, 712 
dlO, 996 

13, 702 

12, 793 

16,969 

16, 966 

50.5 

68.5 

49.5 

31.5 

Tumbler  test  (1-inch  screen): 

Held per  cent. 

Passed  (fines) do. . . 

Fines  through  10-mesh  sieve 

per  cent. 

Weathering  test: 

Time  exposed days. 

Condition 

Water  absorption: 

In  19  days percent. 

In  16  days do. . . 

Average  for  first — 

4 days do. . . 

5 days do. . . 

Specific  gravity  (apparent) 


70.5 

29.5 

85.0 

53 
e A 

22.0 


4. 05 
i.  043 


93.0 

7.0 

91.4 

11 
e A 


13.3 


1.90 

1.275 


a Size  as  used:  Over  J inch,  2.2  per  cent;  ^ inch  to  £ inch,  6 per  cent;  inch  to  ^ inch,  12  percent; 
& inch  to  5V  inch,  19  per  cent;  through  ^ inch,  60.8  per  cent. 

6 Size  as  used:  Over  i inch,  0.8  per  cent;  inch  to  \ inch,  7 per  cent;  inch  to  -fa  inch,  15  per  cent; 
3\,  inch  to  inch,  22.2  per  cent;  through  inch,  55  per  cent. 
cCoal  from  Wehrum,  Pa. 
d Coal  from  Cranston,  R.  I. 

«A=briquets  in  practically  same  condition  as  when  put  out.  Surface  shows  no  signs  of  erosion  or 
pitting.  Briquets  hard  with  sharp  edges  and  fracture  same  as  that  of  new  briquets.  See  Bull.  U.  S. 
Geol.  Survey  No.  332,  1908,  p.  43. 


88  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Laboratory  No 

Air-drying  loss 

Extracted  by  CS2: 

Air-dried 

As  received 

Pitch  in  briquets,  as  received 


Extraction  analyses. 


Pitch. 


4543 

per  cent 

....do....' 

do 99.66 

do 


Fuel. 

Briquets. 

Penn- 

syl- 

vania 

coal. 

Rhode 

Island 

coal. 

Test 

176. 

Test 

184. 

4104 

3141 

4913 

2. 10 

3.40  i 

2.80 

0.03 

.79 

.02 

5.89 

6. 27 

.02  ! 

5.72 

5.02 

6. 25 
5.91 

Occurrence  and  'physical  character. — In  its  mode  of  occurrence  the 
Lower  Kittanning  bed  on  Blackliek  Creek  strongly  resembles  in  its 
main  features  the  same  coal  in  the  districts  along  Conemaugh  River. 
(See  fig.  15.)  The  coal  is  made  up  of  a bench  from  3J  to  4 feet  thick 
and  of  either  one  or  two  lower  benches.  In  a few  places  both 
lower  benches  are  missing  (see  sections  2,  5,  and  6);  the  absence  of 
both  lower  benches  is,  however,  only  local,  for  in  the  same  mine  the 
upper  of  the  two  has  been  observed  at  one  place  but  has  disappeared  a 
short  distance  away.  The  lowest  bench  was  not  observed  about  South 
Fork  or  Johnstown  but  is  persistent  along  Blackliek  Creek.  Here 
and  there  the  main  bench  is  underlain  by  bone.  The  middle  bench  is 
thin,  averaging  not  more  than  4 or  5 inches.  The  lower  bench  is  2 
feet  thick  in  places.  The  two  shale  partings  inclosing  the  middle 
bench  are  thin,  rarely  exceeding  a few  inches  in  thickness.  The 
analyses  (see  pp.  41-42)  represent  coal  from  the  main  bench;  that  from 
the  middle  thin  bench  is  reported  good  but  too  thin  to  mine;  and 
that  from  the  lowest  bench  is  high  in  ash  and  sulphur  and  usually 
too  impure  to  ship.  Below  the  lowest  bench  occurs  a good  deposit 
of  clay,  which  has  never  been  exploited  along  Blackliek  Creek.  The 
roof  of  the  coal  is  either  very  firm  shale  or  sandstone.  The  char- 
acter of  the  roof,  the  irregularity  of  the  floor,  the  general  absence  of 
clay  veins,  and  the  nongaseous  nature  of  the  coal  are  points  in  which 
it  is  similar  to  the  Lower  Kittanning  (Miller)  bed  in  the  Conemaugh 
Valley.  The  coal  is  bright  and  lustrous,  with  a marked  tendency  to 
columnar  cleavage. 


BLACKLICK  CREEK  DISTRICT. 


89 


Figure  15.-Sections  of  the  Lower  Kittanning  (Miller  or  B)  coal  in  the  Blacklick  Creek  district. 

Scale,  1 inch=5  feet. 

1.  Pennsylvania,  Beech  Creek  and  Eastern  Coal  Company  No.  14,  Nanty  Glo. 

2.  Nanty  Glo  Coal  Mining  Company  No.  1,  Nanty  Glo. 

3.  Lincoln  Coal  Company,  Nanty  Glo. 

4.  Ivory  Hill  Coal  Mining  Company,  Nanty  Glo. 

5.  Cardiff  Coal  Company,  5 miles  north  of  Nanty  Glo. 


6.  Country  bank  \\  miles  north  of  Nanty  Glo. 

7,  8.  Commercial  Coal  Mining  Company  No.  3,  4 miles  east  of  Twin  Rocks. 
9.’  Big  Bend  Coal  Mining  Company,  Nonpareil  No.  1,  Twin  Rocks. 

10.  Big  Bend  Coal  Mining  Company,  Big  Bend  Colliery  No.  2,  Twin  Rocks. 

11.  Vinton  Colliery  Company  No.  1,  Vintondale. 


12.  Vinton  Colliery  Company  No.  2,  Vintondale. 

13.  Vinton  Colliery  Company  No.  6,  Vintondale. 

14.  15.  Vinton  Colliery  Company  No.  3,  Vintondale. 

16.  Vinton  Colliery  Company  No.  5,  Vintondale. 

17.  Exposure  in  railroad  cut  east  of  Vintondale. 

18.  19.  Lackawanna  Coal  and  Coke  Company  No.  4,  Wehrum. 

20.  Amos  Rager,  Rummel  Run. 

21.  H.  R.  Dill,  4 miles  northwest  of  Dilltown. 


LOWER  ALLEGHENY  COALS. 

Along  Blacklick  Creek  other  coals  are  known  which  are  below  the 
Lower  Kittanning  bed.  In  the  railroad  cut  near  Twin  Rocks  these 
lower  coals  show,  as  they  do  also  a short  distance  east  of  Weber 
J.ust  where  the  spur  track  turns  in  to  the  collieries  of  the  Big  Bend 
Coal  Company  at  Twin  Rocks  the  following  section  was  measured: 


90  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Section  of  Brookville  and  Clarion  coals  (?)  near  Big  Bend. 

Sandstone,  massive. 

Coal,  10  inches 

Parting,  6 inches.  . . Ft.  in. 

Coal,  1 foot  6 inches  ^Clarion  (A')? 4 2 


Parting,  4 inches . . . 

Coal,  1 foot 

Shale,  black 8 

Shale,  sandy 2-3 

Coal  (Brookville  (A)?) 2 

Clay 3-4 

Sandstone,  massive. 


From  the  massive  sandstones  about  the  place  where  the  section 
was  made  it  is  impossible  to  be  absolutely  sure  that  this  coal  is  in  the 
Allegheny.  The  massive  sandstone  overlying  the  coal  in  the  cut 
may  be  traced  northward  along  the  nose  where  the  river  makes  the 
big  bend  for  some  distance — in  fact,  so  far  as  to  make  it  fairly  certain 
that  it  is  an  Allegheny  sandstone  and  to  corroborats  the  view  that 
the  coal  whose  section  is  given  above  probably  corresponds  to  the 
lowest  coal  or  coals  in  the  Allegheny  formation.  One  of  these  lower 
coals  has  been  opened  about  43  feet  above  the  railroad  tracks  just 
back  of  Twin  Rocks  railroad  station,  but  the  bank  is  now  fallen 
shut.  The  coal  was  reported  as  present  only  in  patches  and  was 
known  in  the  locality  as  the  Three-foot  seam  or  Sulphur  vein. 

The  view  that  the  coal  in  the  cut  near  Twin  Rocks  is  in  the  Alle- 
gheny formation  and  at  its  base  is  strengthened  by  observations 
made  on  the  highway  and  along  the  railroad  farther  west,  near 
Weber.  Near  Commercial  No.  4 mine  the  massive  sandstones  may 
be  observed  close  below  the  Lower  Kittanning  (B)  coal,  and  at  an 
estimated  interval  of  71  to  77  feet  below  are  found  two  coals  thought 
to  correspond  with  the  coals  given  in  the  foregoing  section.  These 
are  regarded,  on  stratigraphic  grounds,  as  Allegheny  coals,  and  the 
massive  sandstone  is  believed  to  be  the  Kittanning  sandstone  member. 
This  heavy  sandstone  coming  at  the  base  of  the  Allegheny  makes  it 
difficult  to  conclude  as  to  the  position  of  the  base  of  this  formation, 
especially  where  the  evidence  has  to  be  obtained  at  scattered  points 
in  different  sections.  This  massive  sandstone,  however,  is  known  to 
occur  at  other  places  in  or  near  the  quadrangle  where  the  relations 
are  plain  and  where  there  is  no  doubt  as  to  its  being  in  the  Allegheny — 
for  instance,  south  of  the  quadrangle,  along  Stony  Creek. 

Near  Weber,  as  near  Twin  Rocks,  the  two  coals  occurring  at  the 
base  of  the  Allegheny  are  too  thin  to  be  worked,  each  being  less  than 
a foot  thick.  The  sections  containing  these  two  coals,  regarded  as 
the  Brookville  (A)  and  the  Clarion  (A')  coals,  are  given  below.  The 
first  section  was  measured  by  Mr.  Martin  and  the  second  and  third 
by  Mr.  Phalen. 


WINDBER  DISTRICT. 


91 


Sections  of  Brookville  and  Clarion  coals  near  Weber. 

1.  Section  on  both  sides  of  railroad  cut. 

Sandstone,  coarse  grained,  thin  and  thick  bedded 

Sandstone,  with  quartz  crystals  and  iron  ore 

Coal,  Clarion  (A7?) 

Fire  clay,  blocky,  fine,  sandy,  fossiliferous 

Sandstone,  fine  grayish 

Sandstone,  blue-black,  shaly 

Sandstone,  fine  grained,  grayish 

Shale,  bluish  black,  with  limestone  nodules 

Coal,  Brookville  (A?) 

Clay,  grayish 


Ft. 

19 

7 

2 

1 


4 

4 


in, 

8 

6 

9 


6 

91 

n 

6 

6 

21 

6 + 


2.  Section  on  north  side  of  cut. 

Sandstone.  Ft.  in. 

Coal  (bony  in  middle),  Clarion  (A7) 9 

Fire  clay,  gravelly,  sandy,  almost  sandstone.  Contains  abun- 
dant organic  impressions  (fossil  imprints) , but  they  are  very  poor . 5 

Shale,  drab  or  dark  gray 4 6 

Coal,  Brookville  (A) If 

Clay 6+ 


3.  Section  on  south  side  of  cut. 

Sandstone.  Ft.  in. 

Coal,  Clarion  (A7) 8-9 

Sandstone,  gnarly,  or  sandy  fire  clay  with  plant  impressions 6 6 

Shale,  dark,  with  concretions.. 4 9 

' Coal,  Brookville  (A) 2 


Shales,  dark,  irregularly  bedded,  upper  part  resembling  fire  clay.  4 


The  dip  from  the  south  to  the  north  side  of  the  track  is  marked, 
even  for  so  short  a distance. 


WINDBER  DISTRICT. 


EXTENT. 

The  Windber  district  of  this  report  includes  the  territory  about  the 
town  of  Windber,  situated  within  the  Johnstown  quadrangle. 


GEOLOGIC  POSITION  OF  THE  COALS. 

All  the  workable  coals  in  this  district  are  found  in  the  Allegheny 
formation,  which  is  above  drainage  level  in  all  the  hills  surrounding 
Windber  and  Scalp  Level.  Of  these  coals,  only  the  Lower  Kittan- 
ning is  now  worked,  but  higher  coals  are  known  to  be  valuable. 

The  usual  main  coals  of  the  Allegheny  formation  are  represented 
in  this  district — that  is,  the  Upper  and  Lower  Freeport  and  the 
Upper,  Middle,  and  Lower  Kittanning  coals.  These  coals  are  also 
visible  in  the  road  sections  in  the  surrounding  hills.  The  distance 
between  the  highest  and  lowest  of  the  five  beds  varies  from  180 
feet  to  about  210  feet,  and,  as  usual,  the  Upper  Kittanning  bed 
occurs  about  midway  between.  A section  of  the  lower  part  of  the 


92  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Allegheny  was  hand  leveled  by  W.  C.  Phalen  at  Scalp  Level,  from 
the  point  where  the  trolley  line  crosses  Paint  Creek.  This  section 
is  as  follows: 


Section  of  lower  Allegheny  rocks  at  Scalp  Level , Somerset  County,  Pa. 


Sandstone  debris.  Ft.  in. 

Coal 10-12 

Clay  ..j, 3 

Shale,  sandy 5 

Shale,  blue 15 

Coal 3-4 


Sandstone,  gnarly 1 

Concealed,  but  with  1 foot  of  Lower  Kittanning  coal  showing  at 

top  (railroad  level) 16 

Shale,  black ■..  5 

Shale,  sandy 10 

Shale 5 

Shale,  debris . .^ 20 

Coal,  10  inches.. . 

Shale,  4 inches.. 

Bone,  6 inches. . . 

Coal,  6 inches 

Concealed ,. 10 

Sandstone,  Pottsville 6+ 


i Brook ville  or  Clarion) 2 2 


According  to  these  measurements,  the  interval  from  the  top  of 
the  Pottsville  to  the  top  of  the  Lower  Kittanning  (B)  coal  is  about 
70  feet,  and  the  single  coal  which  shows  in  the  section  may  be 
the  equivalent  of  the  Brookville  or  Clarion  beds.  At  Scalp  Level, 
where  Paint  Creek  passes  over  bluffs  of  the  Pottsville  formation, 
DTnvilliers  a noted  a thin  seam  of  coal  14  to  18  inches  thick  out- 
cropping just  above  the  water.  This  bed  was  not  observed  and  may 
possibly  be  the  representative  of  the  other  of  these  lower  coals. 

On  the  assumption  that  the  average  thickness  of  the  Allegheny 
from  the  Lower  Kittanning  bed  to  the  Upper  Freeport,  near  Windber, 
is  180  feet  and  the  interval  from  the  top  of  the  Pottsville  to  the 
Lower  Kittanning  is  about  75  feet,  the  thickness  of  the  Allegheny  in 
this  district  is  about  250  feet. 


ALLEGHENY  COALS. 

UPPER  FREEPORT  COAL. 

The  Tapper  Freeport  (E)  coal  is  the  highest  of  the  important  coals 
outcropping  in  the  hills  surrounding  Windber.  It  lies,  according  to 
barometric  measurements,  about  170  to  180  feet  above  the  Lower 
Kittanning  coal,  and  this  interval  remains  fairly  constant  as  far  to  the 
northeast  as  Elton,  where  drillings  show  it  to  be  about  175  feet.  Still 
farther  northeast,  toward  South  Fork  of  Conemaugh  River,  the  inter- 


a Summary  Final  Kept.  Pennsylvania  Geol.  Survey,  voL  3,  pt.  2, 1895,  p.  2248. 


WINDBER  DISTRICT. 


93 


val  increases  to  200  feet.  West  of  Stony  Creek,  in  Somerset  County, 
according  to  the  only  available  information,  which  has  been  pro- 
cured from  diamond-drill'  records,  the  interval  is  about  200  feet. 

Little  definite  information  was  obtained  as  to  the  thickness  of  the 
Upper  Freeport  coal  in  this  district,  as  no  openings  were  located  on  it. 
The  diamond-drill  records  northeast  of  Windber  all  indicate  that  it  is 
workable,  containing  on  an  average  about  3 feet  of  coal.  It  is  known 
to  be  persistent — a fact  which,  in  connection  with  a thickness  of  3 feet, 
seems  to  place  it  among  the  future  sources  of  supply  in  this  region. 

LOWER  FREEPORT  (d)  COAL. 

The  Lower  Freeport  (D)  coal  is  also  persistent  in  this  district;  but 
little  is  known  about  it  except  from  data  furnished  from  drillings. 
Some  of  the  records  from  points  northeast  of  Windber  show  it  to  be 
in  places  3 feet  thick;  others  show  less  promising  sections.  It  is 
possible  that  this  bed  may  be  valuable  in  the  future;  hut  the  data 
obtained  are  insufficient  to  afford  a basis  for  a positive  opinion. 

UPPER  KITTANNING  (c')  COAL. 

The  Upper  Kittanning  (Cement  or  C')  coal  about  Windber  lies 
practically  midway  between  the  Upper  Freeport  and  Lower  Kit- 
tanning beds.  This  is  one  of  the  most  valuable  coals  about  Wind- 

i 

■ 


m 


Figure  16.— Sections  of  the  Upper  Kittanning  (Cement  or  C')coal  in  the  Windber  district.  1,  Balti- 
more and  Ohio  Railroad  south  of  quadrangle;  2,  Stony  Creek  west  of  Ingleside;  3,  east  of  Walsall;  4, 
.head  of  Walsall  Creek.  Scale,  1 inch  = 5 feet. 

her.  Though  it  is  not  worked  on  a commercial  scale,  something  is 
known  at  least  of  its  physical  character  from  prospects  on  it  in  the 
region  north  of  Windber,  within  the.  limits  of  the  Johnstown  quad- 
rangle. In  the  description  of  this  coal  in  the  Johnstown  district  it 
was  stated  that  it  increased  in  thickness  along  Stony  Creek,  south- 
ward from  Moxhom.  As  a matter  of  fact,  the  unusual  thickness  of  5 
feet  6 inches  prevails  generally  north  of  Windber;  6 feet  has  been 
measured  one-half  mile  north  of  Eureka  No.  37  and  5 feet  5 inches 
1 mile  north  of  the  same  mine.  In  both  places  the  roof  was  black 
shale.  (See  also  fig.  16.) 


94  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Section  1 in  figure  16  can  not  be  regarded  as  strictly  in  the  Windber 
district,  as  it  is  on  the  west  flank  of  the  Ebensburg  (Viaduct)  axis, 
some  miles  above  the  mouth  of  Paint  Creek.  Sections  2 and  3 are 
taken  from  country  banks  near  Windber.  Section  4 may  possibly 
be  incomplete,  as  two  sections  measured  about  half  a mile  south  and 
less  than  a mile  west  show  very  nearly  5 feet  of  coal  in  one  and  more 
than  5 feet  in  the  other. 

Enough  is  known  of  the  coal  in  this  district  to  be  certain  that  it 
is  of  workable  thickness.  It  may  not  average  as  thick  as  the  above 
sections  indicate,  but  an  average  of  4 to  5 feet  in  the  hills  north  of 
Windber  is  probably  a conservative  estimate.  Its  quality  is  prob- 
ably equal  to  that  of  the  coal  mined  from  this  bed  near  Johnstown. 
(See  p.  40.)  In  places  the  upper  part  of  the  coal  bed  is  bony  and 
will  have  to  be  discarded  in  mining.  The  roof  is  generally  very  firm 
shale. 

MIDDLE  KITTANNING  COAL. 

The  next  lower  coal,  the  Middle  Kittanning  (C),  is  25  to  30  feet 
above  the  Lower  Kittanning  bed.  A few  of  the  diamond-drill  rec- 
ords to  the  northeast  of  Windber  show  nearly  3 feet  of  coal  in  this 
bed.  This  thickness  is  exceptional.  The  coal  may  prove  valuable 
in  this  district,  but  not  enough  is  known  about  it  to  form  a positive 
opinion. 

LOWER  KITTANNING  COAL. 

Name  and  position. — The  Lower  Kittanning  (Miller  or  B)  coal  in 
the  Windber  district  occurs,  as  stated  above,  at  an  interval  of  about 
170  to  200  feet  below  the  Upper  Freeport  coal  along  the  southern 
edge  of  the  quadrangle.  Immediately  about  Windber  the  interval 
is  somewhat  nearer  the  former  than  the  latter  figure.  The  coal  out- 
crops well  down  in  the  hills  about  the  town,  permitting  the  operations 
to  be  conducted  from  the  outcrop  by  drifts. 

Extent  and  development. — The  coal  appears  above  drainage  level 
on  the  eastern  flank  of  the  Ebensburg  (Viaduct)  anticline  where  this 
fold  approaches  the  Wilmore  Basin,  near  the  southern  edge  of  the 
quadrangle,  and  is  present  in  the  hills  along  Paint  Creek  westward  to 
Stony  Creek.  The  coal  is  above  drainage  level  northward  for  some 
distance  on  Stony  Creek,  where  the  dip  to  the  Johnstown  Basin 
carries  it  below  water  level. 

The  operations  on  this  bed  of  coal  in  the  portion  of  the  Windber 
district  in  this  quadrangle  are  but  a small  part  of  the  coal  industry 
around  Windber.  As  noted  above,  only  two  operations  are  con- 
ducted wholly  within  the  Johnstown  area — namely,  Eureka  Nos.  37 
and  40, 


WINDBER  DISTRICT. 


95 


Chemical  character. — Analyses  Nos.  30  to  32,  pages  41-42,  indicate 
the  composition  of  the  Lower  Kittanning  (Miller)  coal  about  Wind- 
ber.  The  analyses  show  its  carbon  content  to  be  among  the  highest 
in  the  area,  with  a comparatively  small  amount  of  sulphur  and  ash. 

Occurrence  and  physical  character. — The  sections  in  figure  17 
illustrate  the  general  section  of  the  coal  in  the  Windber  district. 
The  first  two  are  the  more  representative,  as  they  are  more  complete, 
showing  the  under  coal  characteristic  of  the  Lower  Kit  tanning  (Miller) 
bed. 

The  main  bench  averages  between  3 Land  4 feet  of  coal.  A small 
rider,  averaging  3 to  4 inches  in  thickness  but  varying  from  1 to  14 
inches,  occurs  from  3J  to  4 feet  above  the  top  of  the  main  bench;  it 
is  noted  in  the  Scalp  Level  section  given  on  page  92.  There  is  also 
usually  present  an  under  coal  lying  from  3 inches  to  2 feet  below  the 


Figure  17.— Sections  of  the  Lower  Kittanning  (Miller  or  B)  coal  in  the  Windber  district.  1,  Baltimore 
and  Ohio  Railroad  south  of  quadrangle;  2,  Berwind- White  Coal  Mining  Company,  Eureka  No.  37, 
Windber;  3,  near  south  edge  of  quadrangle;  4,  near  Walsall.  Scale,  1 inch  = 5 feet. 

main  bench.  This  under  coal  ranges  from  3 to  18  inches  in  thickness 
and  may  be  very  regular. 

The  roof  is  excellent  and  is  either  sandstone  or  sandy  shale.  It 
requires  little  or  no  timbering  except  where  broken  through.  The 
partings  in  the  coal  are  the  usual  “sulphur”  lentils  or  balls,  which 
are  easily  separated  from  the  coal.  Rolls  are  numerous  and  here  and 
there  the  coal  is  completely  pinched  out.  In  places  the  slickensided 
surfaces  associated  with  thin  coal  indicate  movement  akin  to  true 
faulting.  The  under  clay  is  not  worked  in  any  of  the  mines,  so  far  as 
known.  The  coal  in  the  main  bench  is  of  the  lustrous  columnar 
variety. 

LOWER  ALLEGHENY  COALS. 

Though  lower  coals  occur  about  Windber,  they  are  too  thin  to  be 
worked  so  far  as  known.  Section  showing  the  relations  of  these  lower 
Allegheny  coals  are  given  on  page  24. 


96  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

CONEMAUGH  FURNACE  DISTRICT. 

EXTENT. 

Along  the  west  edge  of  the  quadrangle,  in  the  valley  of  Conemaugh 
River,  the  lower  part  of  the  Allegheny  is  brought  down  to  drainage 
level  by  the  steep  dips  along  the  western  flank  of  the  Laurel  Ridge 
anticline.  As  the  Allegheny  or  coal-bearing  formation  outcrops  only 
along  the  river,  the  active  mines  are  confined  to  the  immediate  river 
valley,  and  the  district  is  small.  Within  the  Johnstown  area  there 
are  but  two  active  mines — that  of  the  Johnstown  Coal  Company  and 
that  of  the  Nineveh  Coal  Company.  Both  these  concerns  are  working 
on  the  Lower  Kittanning  (Miller)  bed.  The  dips  carry  this  coal 
below  drainage  level  just  beyond  the  confines  of  the  quadrangle,  and 
farther  west,  in  the  town  of  Seward,  it  lies  at  a depth  of  130  feet,  as 
shown  by  the  shaft  of  the  Seward  Coal  Company. 

ALLEGHENY  COALS. 

UPPER  COALS. 

But  little  definite  information  can  be  given  regarding  the  three 
highest  coals  in  the  Allegheny  formation  in  this  part  of  the  quad- 
rangle, for  the  reason  that  they  have  not  been  worked  even  on  a 
small  scale  and  few  openings  on  them  were  found.  It  is  known, 
however,  that  they  are  present  in  the  hills  north  of  Conemaugh 
River,  outcropping  along  Trout  Run,  on  which  the  Upper  Freeport 
bloom  was  discovered.  At  this  place  a small  opening,  believed  to  be 
on  the  Upper  Kittanning  coal,  showed  the  following  section: 

Section  of  Upper  Kittanning  coal  on  Trout  Run. 


Massive  shale  roof.  Ft.  in. 

Coal . 1 

Bony 4 

Coal * 2 3£+ 


The  Middle  Kittanning  is  fairly  persistent  in  this  district  and  occurs 
about  40  feet  above  the  Lower  Kittanning  (Miller)  bed.  Near  Cramer 
this  bed  measured  as  follows: 

Section  of  Middle  Kittanning  ( C ) coal  near  Cramer. 


Ft.  in. 

Shale 6 

CoaL 1 8 

Bony 2 

Coal ’ , 11 

Clay. 

About  Seward  this  coal  measures  2 feet  6 inches.  At  Seward  also 


the  Lower  Freeport  (D)  coal  is  reported  as  being  about  2 feet  thick, 
capped  by  8 to  12  feet  of  shales  mixed  with  sandstone  slabs  and 
underlain  by  7 feet  of  bluish  massive  shales.  The  overlying  shales 
are  used  in  the  manufacture  of  red  building  brick. 


CONEMAUGH  FURNACE  DISTRICT. 


97 


LOWER  KITTANNING  (b)  COAL. 

Extent  and  development. — The  only  coal  of  commercial  importance 
around  Conemaugh  Furnace  at  present  is  the  Lower  Kittanmng 
(Miller)  bed,  and,  as  stated  above,  there  are  but  two  mines  at  which 
this  coal  is  worked — that  of  the  Johnstown  Coal  Company,  on  the 
north  side  of  Conemaugh  River,  and  that  of  the  Nineveh  Coal  Com- 
pany, on  the  south  side  of  the  river  and  on  the  main  line  of  the 
Pennsylvania  Railroad.  The  coal  here  lies  about  65  to  70  feet* 
above  the  top  of  the  Pottsville  formation.  Farther  west  the  coal 
goes  below  drainage  level  and  is  mined  by  shaft  near  Seward  by  the 
Seward  Coal  Company. 

Chemical  character. — A sample  carload  of  coal  from  this  bed,  col- 
lected and  shipped  by  J.  W.  Groves,  of  the  United  States  Geological 
Survey,  from  a point  on  the  Pennsylvania  Railroad  1 J miles  east  of 
Seward,  Westmoreland  County,  has  been  subjected  to  steaming,  wash- 
ing, coking,  and  briquetting  tests,®  so  that  the  character  and  behavior 
of  the  coal  in  this  part  of  the  quadrangle  are  known.  Two  mine  sam- 
ples were  also  collected  for  chemical  analysis.  The  results  of  the 
chemical  analyses  are  given  on  pages  41-42  (Nos.  33-35)  and  below: 


Chemical  analyses  of  Lower  Kittanning  coal  from  Conemaugh  Furnace  district. 


Laboratory  number. 
Proximate: 

Moisture 

Volatile  matter. 
Fixed  carbon... 

Ash 

Sulphur 

Ultimate: 

Hydrogen 

Carbon 

Nitrogen 

Oxygen 

Ash 

Sulphur 


Steaming 

tests.® 

Briquetting 
tests,  b 

512. 

514. 

198. 

213. 

4726 

4713 

4769 

4885 

3.50 

2.79 

6. 16 

1.23 

19.98 

21.11 

19.23 

20. 58 

67.  71 

67.  79 

64. 38 

67.  74 

8. 81 

8. 31 

10. 23 

10.45 

1.59 

1.91 

2.68 

2.98 

4. 39 

4.42 

4.20 

4.  56 

81.06 

80. 25 

78. 12 

79. 21 

1.06 

1.09 

1.09 

1.12 

2.72 

3.73 

2.83 

1.51 

9. 13 

8.  55 

10.90 

10.58 

1.64 

1.96 

2. 86 

3.02 

a Proximate  analysis  of  fuel  as  fired;  ultimate  analysis  of  dry  fuel  figured  from  car  sample. 
b Proximate  analysis  of  fuel  as  received;  ultimate  analysis  on  dry  basis. 


Only  the  proximate  analyses  are  of  interest  in  this  connection,  and 
these  need  but  little  comment.  They  show  the  usual  high  carbon 
characteristic  of  this  coal  in  the  Johnstown  quadrangle,  together  with 
low  volatile  matter.  The  moisture  is  about  the  same  as  usual  for 
this  coal,  though  perhaps  a trifle  higher.  Ash  and  sulphur  are  both 
higher  than  the  average  for  this  coal  in  the  rest  of  the  area. 


a Bull.  U.  S.  Geol.  Survey  No.  332, 1908,  pp.  216  et  seq. 
69516°— Bull.  447—11 7 


98  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Steaming  tests. — The  steaming  tests  were  not  made  on  the  coal 
itself  but  on  briquets  made  from  it,  and  the  results  are  given  in  the 
table  below.  The  weights  of  water  evaporated  from  and  at  a tem- 
perature of  212°  F.  per  pound  of  dry  fuel  used — 9.65  pounds  in  test 
512  and  8.14  pounds  in  test  514 — indicate  the  standing  of  briquets 
made  from  this  coal.  The  results  should  be  compared  with  the 
results  with  first-class  steaming  coals  given  on  page  37. 

• Steaming  tests  on  Lower  Kit  tanning  coal  from  the  Conemaugh  Furnace  district. 


Duration  of  test 

Heating  value  of  fuel 
Force  of  draft: 


Test512.a 


Test  514.6 


hours. 

B.  t.  u.  per  pound  of  dry  fuel. 


7. 77 
14,495 


7.93 
14, 382 


Under  stack  damper inch  of  water. 

Above  fire do. . . 

Dry  fuel  used  per  square  foot  of  grate  surface  per  hour pounds. 

Equivalent  water  evaporated  per  square  foot  of  water-heating  surface  per  hour.  .do. . . 

Percentage  of  rated  horsepower  of  boiler  developed 

Water  apparently  evaporated  per  pound  of  fuel  as  fired pounds. 

Water  evaporated  from  and  at  212°  F.: 

Per  pound  of  fuel  as  fired do. . . 

Per  pound  of  dry  fuel do. . . 

Per  pound  of  combustible do. . . 

Efficiency  of  boiler,  including  grate per  cent. 

Fuel  as  fired: 


0. 93 
.19 
19. 93 
3.84 
107.7 
7. 70 

9.  32 
9.  65 
10. 76 
64.29 


0. 93 
.23 
27. 52 
4.  47 
125.3 
6.  54 

7. 91 
8. 14 
9.06 
54.  66 


Per  indicated  horsepower  hour pounds. 

Per  electrical  horsepower  hour do. . . 

Dry  fuel: 

Per  indicated  horsepower  hour do. . . 

Per  electrical  horsepower  hour do. . . 


3.03 
3. 75 

2.93 
3. 62 


3. 58 
4.  41 

3.47 

4.29 


a Equal  weights  of  briquets  made  from  washed  coal  (briquetting  tests  215  and  216,  p.  100). 
b Equal  weights  of  briquets  (briquetting  tests  208  and  209,  p.  100). 


Test  512  on  briquets  from  tests  215  and  216  (equal  weights); 
briquets  burned  freely,  with  intense  heat  and  no  smoke;  31  per  cent 
clinker.  Test  514  on  briquets  from  tests  208  and  209  (equal  weights) ; 
briquets  burned  freely,  with  intense  heat  and  no  smoke;  50  per  cent 
clinker. 

Coking  tests. — The  results  of  the  coking  tests  on  this  coal  are  given 
below,  together  with  analyses  of  the  coal  and  resulting  coke. 


Coking  tests  on  Lower  Kittanning  coal  from  Conemaugh  Furnace  district. 


[Run-of-mine  coal,  finely  crushed.] 


Duration  of  test . 
Coal  charged 

Coke  produced.. 

Breeze  produced 
Total  yield 


Test  179 

Test  182 

(raw). 

(washed). 

hours. . 

68 

78 

..pounds.. 

13,070 

11,760 

( do 

8,129 

7,350 

(per  cent.. 

62.20 

62.50 

(pounds... 
(per  cent. . 

420 
3. 21 

529 

4.50 

do 

65.  41 

67.00 

Test  179  yielded  soft,  dense  coke  light  gray  and  silvery  in  color, 
with  high  ash  and  sulphur.  Test  182  yielded  soft,  dense  coke  gray 
in  color.  Ash  and  sulphur  were  reduced  by  washing.  There  was  no 
improvement  in  physical  appearance. 


CONEMAUGH  FURNACE  DISTRICT. 


99 


Analyses. 


Test  179. 

Test  182. 

Coal. 

Coke. 

0.30 
.28 
84.95 
14.  47 
2. 31 

Coal. 

Coke. 

Moisture 

3. 91 
16. 35 
68. 30 
11.44 
2.  78 

6. 30 
17. 04 
69.  58 
7.08 
1.34 

0.51 
.58 
89. 85 
9. 06 

1.11 

Volatile  matter 

Fixed  carbon 

Ash 

Sulphur 

M7ashing  tests. — Results  of  washing  tests  are  given  below.  The 
figures  indicate  that  finer  crushing  is  advantageous.  The  loss  of 
“good  coal”  (by  which  is  meant  all  coal  of  a quality  equal  to  or  bet- 
ter than  that  of  the  washed  coal)  in  the  refuse  will  not  exceed  2 per 
cent. 


Float  and  sink  tests  on  Lower  Kittanning  coal  from  Conemaugh  Furnace  district: a 


Percentage  of 
float. 

Analyses. 

Number  of  test. 

Size 

used 

Specific 
gravity 
of  solu- 
tion used. 

Sink 

(per 

Ash. 

Sulphur. 

(inch). 

To 

refuse. 

To 

total 

sample. 

cent). 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

On  raw  coal  (preliminary): 

1 

1 

1.35 

83 

17 

4.95 

53 

0.93 

67 

2 

1.42 

88 

12 

5. 66 

46 

1.24 

57 

3 

3 

1.45 

88 

12 

4. 72 

55 

1.02 

64 

4 

| 

1.52 

89 

11 

6.07 

42 

1.09 

62 

On  refuse  (float): 

1 

1.35 

17.20 

3. 91 

5.42 

1.69 

2 

1.41 

18. 50 

4.20 

5.69 

1.69 

3 

1.45 

19.88 

4.51 

6.45 

2. 15 

4 

1.53 

20.20 

4.59 

7.89 

2.08 

a Duration  of  test,  2f  hours.  Size  as  used,  through  1-inch  screen.  Jig  used,  special;  speed,  70  revolutions 
per  minute;  stroke,  inches.  Raw  coal,  22.21  tons;  washed  coal,  17.25  tons,  78  per  cent;  refuse,  4.96  tons, 
22  per  cent. 

Analyses. 


Sample  tested. 

Mois- 

ture. 

Ash. 

Sulphur. 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

Per 

cent. 

Per 

cent 

reduc- 

tion. 

Raw  coal,  car  sample 

4.00 
6.48 
10. 21 

10.54 
6. 76 
46.25 

2.85 

1.30 

17.40 

Washed  coal 

36 

54 

Refuse 

Briquetting  tests. — Seven  briquetting  tests  were  made,  three  on  raw 
and  four  on  washed  coal.  Briquets  from  both  the  English  and  the 
Renfrow  (American)  machines  had  similar  appearance,  with  smooth, 
hard  surface,  were  very  brittle,  and  broke  with  a glossy  fracture  and 


100  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


sharp  edges.  The  percentage  of  binder  (water-gas  pitch)  seemed  to 
have  little  effect  on  brittleness,  although  Renfrow  briquets  with 
8 per  cent  binder  were  handled  with  less  breakage.  There  was  no 
noticeable  difference  between  the  briquets  made  from  raw  and  those 
from  washed  coal. 

For  analyses  of  coal  used  in  briquets  see  page  97  (those  from  bri- 
quetting tests  208  and  209  under  steaming  test  514;  from  briquetting 
tests  212,  215,  and  216  under  steaming  test  512). 

Briquetting  tests  on  run-of-mine  coal  from  Conemaugh  Furnace  district. 


[Water-gas  pitch  binder.) 


Test 

198. 

Test 

208. 

Test 

209. 

Test 

212. 

Test 

213. 

Test 

215. 

Test 

216. 

Details  of  manufacture: 

Machine  used 

Eng. 

Renf. 

Renf. 

Renf. 

Renf. 

Eng. 

Eng. 

Temperature  of  briquets 

158 

158 

158 

158 

158 

176 

176 

Binder- 

Laboratory  number 

4683 

4683 

4683 

4683 

4683 

4683 

4683 

Amount 

..percent.. 

6 

7 

8 

7 

8 

6 

7 

Weight  of— 

Fuel  briquetted 

...pounds.. 

3,200 

4,500 

8,000 

6,500 

6,500 

6,400 

3,300 

Briquets,  average 

do.... 

3.52 

0.451 

0.457 

0. 427 

0.458 

3.63 

3.44 

Heat  value  per  pound— 

Fuel  as  received 

...B.  t.  u.. 

13,347 

13,347 

13,347 

14, 639 

14,639 

14,639 

14,639 

Fuel  as  fired 

do 

13, 198 

13,981 

13,981 

13,896 

13,988 

13,988 

Binder 

do 

16,637 

16,637 

16, 637 

16,637 

16, 637 

16, 637 

16,637 

Drop  test  (1-inch  screen): 

Held 

. .per  cent. . 

74.8 

19.5 

26.0 

23.0 

19.5 

74.6 

71.9 

Passed 

do 

25.2 

80.5 

74.0 

77.0 

80.5 

25.4 

28.1 

Tumbler  test  (1-inch  screen): 

Held 

do 

71.0 

54.0 

61.5 

67.0 

64.0 

74.0 

70.5 

Passed  (fines) 

do 

29.0 

46.0 

38.5 

33.0 

36.0 

26.0 

29.5 

Fines  through  10-mesh  sieve... 

do 

65.4 

86.8 

86.4 

91.6 

87.3 

63.2 

70.4 

Water  absorption: 

In  13  days 

do 

14.5 

15.5 

15.0 

19.0 

14.5 

9.5 

11.0 

Average  for  first  5 days 

do 

2.34 

2. 78 

2.66 

3.1 

2.50 

1.56 

1.56 

Specific  gravity  (apparent) 

1. 141 

1.11 

1.127 

1.043 

1.144 

1.148 

1.121 

Tests  198,  208,  and  209.  Size  used:  Over  J inch,  0.8  per  cent;  V<j  inch  to  I inch,  3.6  per  cent;  inch  to  TV 
inch,  11.2  per  cent;  ^ inch  to  55  inch,  27  per  cent;  through  inch,  57.4  per  cent. 

Tests  212,  213,  215,  and  216  (on  washed  coal).  Size  as  used:  Over  I inch,  0.8  per  cent;  ^ inch  to  \ inch, 
4.8  percent;  inch  to  TV  inch,  16  per  cent;  & inch  to  5V  inch,  26  percent;  through  ^ inch,  52.4  percent. 


Extraction  analyses. 


Pitch. 

Fuel. 

Briquets. 

Test 

198. 

Tests 

208,209. 

Test 

213. 

Tests 

215,216. 

Laboratory  No 

4683 

4498 
3. 10 

1.02 

.99 

4769 

5.50 

5.60 
5. 29 
5.00 

4713 

2.00 

6. 86 
6.  72 
6.  49 

4885 

0.60 

8.03 

7.98 

7.92 

4726 
3. 10 

6.90 
6.  61 
6.37 

Air-drying  loss . per  cent 

Extracted  by  CS2: 

Air-dried do 

As  received do 

Pitch  in  briquets  as  received do. . . 

89.31 

CONEMAUGH  FURNACE  DISTRICT. 


101 


Occurrence  and  physical  character. — The  sections  in  figure  18  indi- 
cate the  thickness  of  the  Lower  Kittanning  coal,  its  under  benches, 
and  the  character  of  its  roof  and  floor  in  the  Conemaugh  Furnace 


123 


Figure  18.— Sections  of  the  Lower  Kittanning  (Miller  or  B)  coal  in  the  Conemaugh  Furnace  district. 
1,  2,  Johnstown  Coal  Company,  north  of  Conemaugh  River;  3,  Nineveh  Coal  Company,  Seward  mine, 
south  bank  of  Conemaugh  River.  Scale,  1 inch  = 5 feet. 

district.  In  addition  to  the  sections  shown  in  the  figure,'  the  following 
were  measured: 

Section  of  Lower  Kittanning  coal  on  Laurel  Ridge,  near  Cramer. 


Shale  roof.  Ft.  in. 

Coal 3 7 

Shale 6 


Fire  clay. 

Section  of  Lower  Kittanning  coal  at  mine  of  Seward  Coal  Company,  Seward. 


Shale  roof.  Ft.  in. 

Coal 3 3 

Shale  or  clay 6 

Coal 1 

Clay 6 

Coal 6 

Fire  clay,  hard 1 

Clay,  soft  (reported) 1 4 


The  coal  near  Conemaugh  Furnace  and  Seward  is  comparable  in 
every  way  with  the  corresponding  coal  as  mined  farther  east  near 
Johnstown,  South  Fork,  Blacklick  Creek,  and  Windber.  In  this  par- 
ticular district  the  bed  was  measured  and  studied  in  three  mines  and 
seen  at  one  country  bank.  The  main  bench  ranges  from  3 feet  3 
inches  to  3 feet  9 inches.  Below  this,  one  and  in  places  two  lower 
benches  are  found.  The  first  ranges  in  thickness  from  6 to  20  inches 
and  is  separated  from  the  main  bench  by  a shale  parting  usually  not 
more  than  6 inches  thick;  this  bench  is  used  at  Seward  by  the  brick 
company  to  burn  bricks.  The  second  lower  bench  is  about  6 inches 
thick,  and  the  underlying  clay  is  reported  as  thick  as  17  feet,  only 
6 feet  of  which  is  considered  of  brickmaking  grade.  The  roof  of  the 
coal  is  firm  shale  and  the  usual  rolls  in  the  floor  are  present. 


102  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

COAL  MINING. 

Two  general  systems  of  working  coal  were  employed  in  the  Johns- 
town quadrangle  when  this  work  was  done — the  room  and  pillar 
system  and  the  long-wall  system.  The  former  is  in  most  common 
use,  but  two  of  the  mines  along  Blacklick  Creek  (Nos.  1 and  3 of  the 
Vinton  Colliery  Company)  have  used  the  long-wall  system. 

ROOM  AND  PILLAR  SYSTEM. 

General  description. — The  diagram  or  plan  of  the  workings  of  one 
of  the  mines  in  the  quadrangle  given  in  figure  19  conveys  some  idea  of 
the  methods  generally  employed  in  the  room  and  pillar  method  of 
mining  coal. 

Most  of  the  mines  in  the  quadrangle  are  drift  mines  and  work  coal 
which  averages  between  3 and  4 feet  in  thickness.  For  this  reason, 
in  the  headings  where  hauling  is  done  the  roof  is  generally  removed 
so  as  to  allow  between  5 and  5^  feet  above  the  rail  or  nearly  6 feet  in 
the  clear.  The  main  heading  is  usually  driven  straight  and  is  cut 
through  rolls,  which  are  very  common  in  the  Lower  Kittanning 
(Miller)  coal,  the  most  important  bed  of  the  area.  If  the  rolls  are  too 
pronounced,  however,  the  main  heading  may  be  curved  around  them. 

The  main  entry  or  heading  is  usually  run  about  10  feet  wide;  in 
some  mines  it  is  as  narrow  as  9 feet  and  in  a few  as  wide  as  12  feet; 
in  still  others  the  width  of  the  main  headings  ranges  from  18  to  25 
feet,  but  in  such  mines  the  rock  is  gobbed  underground.  Wide  head- 
ings are  not  usual.  The  main  airways  appear  to  be  about  as  wide 
as  the  main  headings,  and  the  pillar  left  between  the  two  averages 
about  50  feet. 

Cross  or  side  headings  are  run  from  the  main  headings  either  at  a 
considerable  inclination  or  at  right  angles.  The  width  of  the  cross 
headings  varies  but  is  commonly  about  15  to  18  feet.  One  mine  at 
South  Fork  reported  cross  headings  only  7 to  8 feet  wide.  A few 
mines  near  Johnstown  reported  cross  headings  as  broad  as  21  and  24 
feet,  but  here  it  is  possible  that  much  of  the  rock  may  be  gobbed 
underground.  About  South  Fork  some  of  the  larger  mines  reported 
cross  headings  550  feet  apart.  In  turning  rooms  from  the  cross 
headings  the  turn  may  be  about  9 feet  long  and  15  feet  wide,  but  the 
practice  may  vary  considerably  from  these  figures. 

The  dimensions  of  rooms  vary  within  narrow  limits.  The  width 
ranges  from  21  to  40  feet;  24-foot  rooms  are  very  common,  but  those 
in  excess  of  30  feet  are  rare.  About  South  Fork  the  roof  of  the  Lower 
Kittanning  (Miller)  coal  has  caused  trouble  in  places,  and  some 
rooms  have  been  lost  on  account  of  running  them  too  wide;  in  the 
mines  where  this  difficulty  was  encountered  a 21 -foot  room  with  15  to 
20  foot  pillars  has  given  the  best  satisfaction.  The  length  of  the 


COAL  MINING. 


103 


Figure  19. — Diagram  illustrating  room  and  pillar  method  of  mining  in  Johnstown  quadrangle. 


104  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

rooms  in  the  larger  mines  is  usually  300  feet,  but  ranges  from  225  to 
360  feet,  the  latter  length  being  fairly  common  near  South  Fork  and 
along  Blacklick  Creek.  In  many  of  the  smaller  mines  the  length  of 
rooms  is  less  than  100  feet. 

The  width  of  pillars  between  rooms  is  generally  30  feet,  but  in  some 
of  the  mines  where  the  covering  is  unusually  heavy  more  pillar  has 
to  be  left,  and  at  South  Fork  some  of  the  larger  mines  report  34  to  36 
foot  pillars.  As  stated  above,  a 15  to  20  foot  pillar  gives  the  best 
satisfaction  in  certain  mines.  Pillars  27,  24,  and  21  feet  wide  are  also 
used  at  a few  mines.  A 60-foot  pillar  was  reported  from  a couple  of 
mines.  A “skip”  is  a crosscut  between  two  adjacent  rooms.  Its 
length,  of  course,  is  the  width  of  a pillar;  its  width  varies  from  10  to 
20  feet.  Pillars  are  worked  back  from  the  room  face  within  60  feet  of 
the  cross  headings  until  all  the  rooms  in  the  cross  headings  are  worked 
out.  The  roof  is  allowed  to  cave  after  the  coal  is  worked  out. 

The  methods  of  ventilation,  drainage,  and  haulage  of  coal  to  the 
surface,  together  with  the  mining  methods  employed,  vary  widely. 
Some  of  the  mines  in  the  quadrangle  are  among  the  largest  in  the 
State  and  employ  hundreds  of  men.  Such  mines  have  extensive 
underground  workings  and  employ  the  most  elaborate  and  expensive 
systems  to  insure  the  safety  of  the  lives  of  the  men  and  the  cheapest 
and  most  expeditious  means  of  transferring  coal  from  mining  breasts 
to  coal  cars.  At  Windber,  for  instance,  machine  mining  is  practiced 
almost  altogether  at  Eureka  No.  37,  compressed-air  machines  being 
used.  Hauling  is  done  by  electricity  and  ventilation  by  fans.  The 
drainage  is  natural  and  by  pump.  Of  Eureka  No.  40  mine,  which  is 
the  latest  in  the  Windber  territory,  J.  T.  Evans,  mining  inspector  of 
the  sixth  bituminous  district  of  Pennsylvania,  says:3  “It  will  be  the 
model  mine  of  the  district.” 

Ventilation. — Ventilation  is  effected  by  natural  methods,  furnace 
and  stack,  or  fan.  In  the  smaller  mines  the  first  two  methods  are  in 
common  use,  but  in  the  larger  mines  fan  ventilation  has  to  be  em- 
ployed, The  variety  of  the  fans  used  is  great;  the  size  of  fan  and  the 
number  of  revolutions  made  per  minute  depend  entirely  on  local 
coditions.  The  motive  power  used  in  driving  the  fans  is  compressed 
air,  electricity,  steam,  etc. 

Drainage. — Drainage  is  either  natural  or  artificial.  In  most  of  the 
smaller  mines  and  in  some  of  the  larger  workings  natural  drainage  is 
used.  Artificial  drainage  is  accomplished  by  pumps  driven  by  com- 
pressed air,  steam,  or  electricity;  hand  pumps  are  also  used. 

Haulage. — In  the  smaller  mines  both  hand  haulage  and  mule 
haulage  are  employed.  In  the  larger  mines  mule  haulage  is  used 
almost  exclusively  as  an  auxiliary;  the  mules  haul  the  loaded  mine 


a Rept.  Pennsylvania  Dept.  Mines,  pt.  2, 1906,  p.  377* 


COAL  MINING. 


105 


cars  to  the  foot  of  slopes  or  planes  or  to  the  electric  tramways,  and 
the  loaded  cars  are  hauled  out  by  wire  ropes  or  electric  locomotives. 
The  overhead- trolley  system  is  in  common  use  and  at  South  Fork  the 
third-rail  system  is  used  in  one  of  the  mines. 

Tipples  are  of  various  makes.  The  old-fashioned  cradle  tipple  is 
still  the  most  popular,  but  an  automatic  dump  is  used  at  some  of  the 
larger  mines  at  South  Fork  and  on  Blacklick  Creek,  a crossover 
patent  in  at  least  two  mines  on  Blacklick  Creek,  and  a kind  of  rotary 
tipple  at  one  mine  in  the  Blacklick  Creek  district.  At  the  Cone- 
maugh  slope  the  coal  is  dumped  at  the  mine  mouth  into  buckets  of 
1,000  pounds  capacity,  which  are  then  conveyed  by  electric  power 
from  the  north  side  of  Conemaugh  River  over  the  Pennsylvania 
Railroad  to  the  Franklin  plant  of  the  Cambria  Steel  Company. 

Mining  methods . — The  mining  methods  employed  in  the  Johnstown 
quadrangle  are  hand  or  pick  mining  and  machine  mining.  In  some 
of  the  larger  mines . machines  are  used  almost  exclusively,  but  as  a 
general  thing  a combination  of  pick  and  machine  mining  is  found 
more  satisfactory. 

LONG- WALL  SYSTEM. 

The  conveyor  method  of  the  long-wall  system  of  mining  coal  has 
been  used  at  collieries  Nos.  1 and  3 of  the  Vinton  Colliery  Company  at 
Vintondale,  in  the  Blacklick  Creek  district  (fig.  20).  It  has  been 
abandoned  for  some  years  in  this  district.  The  long-wall  system  is 
the  one  most  commonly  used  in  the  coal  mines  of  Europe,  where 
it  is  regarded  as  being  much  more  economical  of  the  coal  than  the 
room  and  pillar  method.  For  this  reason  it  was  recommended  in  the 
report  to  the  Secretary  of  the  Interior  by  Messrs.  Watteyne,  Meissner 
and  Desborough,®  the  three  foreign  experts  recently  selected  for  the 
investigation  of  mine  explosions  in  the  United  States.  The  long-wall 
system  has  a number  of  modifications,  that  used  in  the  Blacklick 
Creek  district  and  commonly  referred  to  as  the  conveyor  method  being 
one  of  them.  Figures  21  and  22  illustrate  the  method  as  formerly 
practiced  at  Vintondale.  The  coal  bed  worked  is  the  Lower  Kittan- 
ning (Miller  or  B)  bed.  It  usually  runs  3 feet  6 inches  thick  near 
Vintondale,  and  its  maximum  and  minimum  thickness  may  be  taken 
as  3 feet  10  inches  and  3 feet  3 inches,  respectively.  Below  the  main 
bench,  from  which  it  is  separated  by  8 to  10  inches  of  shale,  is  a coal 
ranging  from  2 to  10  inches  in  thickness.  The  roof  of  the  coal  is  hard 
shale  and  is  a most  excellent  cover,  though  it  has  marked  slips  or 
crevices.  The  coal  is  bound  very  tightly  to  both  roof  and  floor. 
The  average  thickness  of  the  cover  is  about  180  to  200  feet.  The 
territory  of  the  mines  is  long  and  narrow,  and  this,  together  with  the 


a Bull.  U.  S.  Geol.  Survey  No.  369, 1908,  p.  6. 


106  MINERAL  RESOURCES  OF  • JOHNSTOWN,  PA.,  AND  VICINITY. 


Figure  20. — Plan  showing  long-wall  method  of  mining  as  employed  at  Vinton  collieries  Nos.  1 and  3, 

Vintondale 


COAL  MINING. 


107 


heavy  pitch  of  the  coal  (see  PI.  I),  makes  the  successful  working  of 
the  bed  by  the  room  and  pillar  method  difficult.® 

The  long-wall  method  as  first  practiced  at  Vintondale  differs  some- 
what from  the  method  used  there  later.  At  the  beginning  of  the  op- 
erations in  this  region  the  faces  of  the  coal  were  worked  by  passing  the 
mine  cars  at  one  end  of  the  face,  along  the  face,  and  out  at  the  opposite 
end  when  loaded.  The  results  were  only  fair,  as  the  roof  and  the 
steep  grades  both  gave  trouble.  In  the  other  mines  working  at 
Vintondale  at  this  time  no  marked  slips  or  cracks  in  the  roof  had 
been  noticed  and  it  was  naturally  inferred  that  these  conditions 
would  prevail  generally;  but  after  the  long-wall  faces  had  been  in 


Figure  21. — Plan  of  workings,  single  long-wall  conveyor  system.  (From  an  article  by  J.  I.  Thomas  in 
Mines  and  Minerals,  November,  1907,  pp.  200-203.  Reproduced  by  permission.) 


operation  for  some  time  marked  slips  were  encountered  almost 
exactly  in  line  with  the  face  of  the  coal,  and  it  was  found  very  difficult 
to  keep  the  roadway  open  when  these  slips  occurred  at  the  working 
face. 

Another  reason  for  abandoning  this  method  of  working  was  the 
difficulty  of  controlling  mine  cars  on  the  heavy  grades.  Not  only 
wrecks  but  delays  were  caused  by  mine  cars  getting  beyond  the 
working  faces.  If  the  roof  conditions  had  been  more  favorable,  the 
proposed  method  of  working  would  have  made,  with  slight  modifica- 
tions, an  excellent  arrangement  for  the  use  of  the  conveyor  system.5 

a A description  of  the  method  of  mining  the  coal  in  this  region  was  read  by  Mr.  Clarence  R.  Claghorn  at 
the  February,  1900,  meeting  of  the  North  of  England  Institute  of  Mining  and  Mechanical  Engineers  (Trans. 
Inst.  Min.  Eng.,  vol.  18, 1900,  pp.  351  et  seq.). 
b Ware,  R.  G.,  Trans.  Inst.  Mm.  Eng.,  vol.  29, 1906,  pp.  462-474. 


108  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


To  overcome  the  delays  and  difficulties,  C.  R.  Claghorn  proposed 
that  a conveyor  should  be  installed  along  the  long-wall  faces  and  that 
the  mine  cars  should  be  run  on  a semipermanent  road  under  the  head 
end  of  the  conveyor  and  there  loaded  instead  of  being  passed  along  the 
face.  From  the  first  the  conveyor  was  a success. 

The  following  descriptions  of  the  working  methods  at  Vintondale 
are  by  Mr.  J.  I.  Thomas,  assistant  superintendent  of  the  Vinton  col- 
lieries a wffien  the  field  work  on  the  report  was  done : 

The  block  work,  which  is  a modification  of  long-wall  mining,  was  first  started  in  the 
No.  3 mine  of  this  company  seven  years  ago.  At  the  outset  cars  were  run  around  the 
working  face  and  loaded.  This  method  brought  only  fair  results  owing  to  the  necessity 
of  using  small  cars,  steep  grades,  and  difficulty  in  keeping  roadways  open.  Arrange- 
ments were  then  made  for  the  placing  of  a conveyor  along  the  face,  allowing  thfe  cars 
to  be  run  under  the  head  end  to  be  loaded. 


Figure  22.— Plan  of  workings,  triple  long-wall  conveyor  system.  (From  an  article  by  J.  I.  Thomas  in 
Mines  and  Minerals,  November,  1907,  pp.  200-203.  Reproduced  by  permission.) 

The  first  conveyor,  which  was  made  entirely  of  wood,  was  a cumbersome  affair 
and  much  time  was  consumed  in  moving  it  laterally  along  the  face  after  the  cut  had 
been  loaded  out,  but  after  a year’s  trial  the  results  obtained  were  so  gratifying  that 
metal  conveyors  were  designed  and  ordered  and  preparations  were  made  to  employ 
this  system  on  a much  larger  scale. 

The  conveyor  system  is  very  flexible  and  numerous  methods  of  working  are  applica- 
ble, as  the  condition  of  the  territory  demands. 

In  Vintondale,  at  present,  there  are  two  different  arrangements — that  is,  the  single 
conveyor  method,  which  has  been  mentioned,  and  the  triple-conveyor  system,  by 
which  two  face  conveyors  dump  alternately  into  a third  conveyor,  which  in  turn 
dumps  into  the  mine  cars.  Both  air  and  electricity  are  used  as  the  driving  power. 


o Coal  Min.  Inst.  America,  June  meeting,  1907.  Mine  and  Quarry,  vol.  2,  No.  3,  February,  1908,  pp.  193 
et  seq.  Mines  and  Minerals,  November,  1907,  pp.  200-203. 


COAL  MINING. 


109 


In  the  No.  3 mine,  where  the  single-conveyor  system  is  being  used  with  compressed 
air  as  power,  the  main  heading  and  air  course  are  driven  up  the  pitch  through  the  center 
of  the  property.  Cross  headings  are  driven  off  the  main  at  intervals  of  400  feet  and 
run  to  the  outcrop.  These  headings  are  20  feet  wide,  with  an  8-foot  roadway  carried 
next  to  the  pillar,  which  is  40  feet  thick.  Barrier  pillars  of  75-foot  thickness  are 
maintained  on  each  side  of  the  main  entries.  Block  headings  are  driven  perpendic- 
ularly off  the  cross  entries  at  265  feet  centers.  This  allows  a solid  face  of  250  feet. 
These  block  headings  are  driven  15  feet  wide,  but  bottom  is  lifted  only  7 feet  wide  near 
the  rib  and  of  such  depth  to  allow  a clearance  of  6 feet  from  the  top  of  rail.  The  remain- 
ing width  acts  as  a shelf  for  the  support  of  the  drive  and  long-wall  machine.  As  the 
block  headings  are  driven  for  a distance  of  350  feet  into  the  solid  coal,  it  is  found 
necessary  to  carry  along  a good  line  of  bratticing  for  the  purpose  of  ventilation. 

The  block  nearest  the  outcrop  is  first  attacked.  On  this  block  it  is  necessary  to 
maintain  an  areaway  at  the  rear  end.  This  is  done  by  driving  along  with  the  block  a 
place  4 feet  wide,  leaving  a pillar  10  feet  thick  between  it  and  the  edge  of  the  block. 
The  coal  is  extracted  to  within  25  feet  of  the  upper  heading,  when  the  conveyor  is 
removed  to  the  next  block,  which  is  worked  out  in  the  same  manner;  and  so  on  until 
the  coal  in  the  whole  tier  of  blocks  is  recovered.  In  the  meantime  the  pillar  left  by 
the  block  and  the  chain  pillars  are  being  mined  by  hand.  The  time  consumed  in 
removing  equipment  from  one  block  to  another  is  usually  about  fifteen  hours. 

The  type  of  conveyor  consists  of  a trough  or  pan  made  of  sheet  steel  one-eighth 
inch  thick,  12  inches  wide  at  the  bottom,  18  inches  wide  at  the  top,  and  6 inches  high, 
set  on  strap-iron  standards.  The  conveyor,  which  is  250  feet  in  length,  is  made  up  in 
sections  of  6, 12, 15,  and  18  foot  lengths,  connected  together  by  means  of  one-half  inch 
flat-headed  bolts,  countersunk.  The  front  is  inclined  for  a distance  of  45  feet  to  allow 
clearance  for  mine  cars  to  pass  under.  The  rear  end  is  inclined  for  15  feet  to  compen- 
sate for  the  size  of  sprocket  wheel.  A return  runway  for  the  chain  is  afforded  below 
the  pans  by  angle  irons. 

A cast-iron  driving  sprocket  18  inches  in  diameter  and  13-inch  face  is  attached  to  the 
front  end.  On  the  shaft  of  this  sprocket,  which  is  extended  12  inches  beyond  one  of 
the  bearings,  is  keyed  a 12-tooth  16-inch  diameter  sprocket,  which  connects  with  the 
driving  mechanism.  The  rear-end  section  consists  of  a framework  made  up  of  two 
I-beams,  6 feet  long  and  strongly  braced,  on  which  rest  the  take-up  boxes  for  keeping 
the  chain  in  adjustment  and  the  rear  sprocket  wheel  over  which  the  chain  returns. 

The  conveyor  chain  is  made  of  either  steel  or  malleable  cast  iron,  held  together 
by  bolts,  the  ends  of  which  may  be  riveted  or  fitted  with  nuts.  As  it  is  impracticable 
to  secure  a chain  that  will  not  break,  they  are  designed  so  that  repair  can  be  made 
expeditiously. 

The  power  is  carried  to  the  different  machines  by  means  of  a 2-inch  pipe,  which 
is  run  from  the  main  supply  along  the  lower  heading  to  the  top  of  the  block  heading. 
A connection  is  here  made  with  the  hoisting  engine.  The  line  is  carried  on  props 
down  the  block  heading  to  the  conveyor,  where  it  is  connected  by  means  of  a 2J-inch 
wire-wound  rubber  hose  to  a 2-inch  pipe  that  runs  the  entire  length  of  the  block  and 
attached  to  the  conveyor.  This  pipe  has  outlets  with  2-inch  stopcocks  at  intervals 
of  50  feet,  to  which  the  hose  of  the  mining  machines  and  air  drills  may  be  attached. 
This  arrangement  necessitates  carrying  only  a short  length  of  hose  on  these  machines 
instead  of  one  reaching  the  whole  length  of  the  block. 

From  the  end  of  the  conveyor  a Id-inch  pipe  is  run  to  the  air  engine.  In  this  pipe 
is  a valve,  which  is  connected  to  a rod  that  reaches  to  the  head  end  of  the  conveyor. 
It  is  from  this  point  that  the  conveyor  is  controlled  when  running.  As  the  air  line 
needs  to  be  shortened  5 feet  nearly  every  day,  several  sections  of  different  lengths 
are  kept  near  at  hand,  so  that  this  change  can  be  quickly  made. 

The  cars  are  handled  to  the  conveyor  by  means  of  a double  cylinder,  with  an  8 by 
10  inch  double  friction-drum  hoisting  engine.  The  drums  work  loose  on  the  shaft 


110  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


independent  of  each  other  and  are  equipped  with  a powerful  differential  brake  that 
will  hold  any  load  the  engine  will  hoist;  500  feet  of  f-inch  rope  is  reeled  on  each  drum. 
A small  hand  drum,  on  which  is  reeled  150  feet  of  5-inch  rope,  is  used  to  lower  the 
cars  around  the  curve. 

The  cars  are  dropped  into  the  lower  heading  from  the  main  haulage  and  pulled, 
either  with  mules  or  a small  engine,  to  the  top  of  the  block  heading.  Here  the  rope 
of  the  small  drum  is  attached  to  the  coupling  between  the  first  and  second  car  and 
the  cars  pushed  around  the  curve.  One  of  the  ropes  of  the  hoist  is  now  attached  to 
the  rear  end  of  the  trip,  which  is  usually  ten  cars,  and  the  small  rope  is  freed.  The 
trip  is  then  dropped  to  the  conveyor  to  be  loaded.  Another  trip  is  attached  to  the 
other  rope  of  the  hoist  in  the  same  manner.  This  trip  is  held  on  the  block  entry 
until  the  first  trip  is  loaded.  This  having  been  accomplished,  the  loaded  trip  is 
dropped  to  the  bottom  of  the  block  heading  and  the  rope  disengaged.  The  driver 
here  takes  the  cars  and  hauls  them  to  the  main  haulage.  The  rope  is  then  pulled  to 
the  top  of  the  block  heading  and  attached  to  the  cars,  as  described.  In  the  mean- 
time the  empty  trip  on  the  block  heading  has  been  dropped  to  the  conveyor  and 
started  to  be  loaded.  This  change  usually  occupies  two  to  three  minutes.  Electric 
signal  wires  are  run  the  length  of  block  headings,  by  which  the  head  man  signals 
the  engine  boy. 

The  drive,  which  is  a small  double-cylinder  engine  with  reduced  gearing,  is  mounted 
on  a frame  and  attached  to  the  conveyor.  The  power  is  transmitted  by  means  of  a 
steel  thimble  roller  chain  to  the  sprocket  on  the  drive  shaft  of  the  conveyor. 

The  drill  used  for  boring  the  holes  is  an  ingenious  tool;  the  weight  of  auger  and 
drill  does  not  exceed  20  pounds.  The  machine  is  a small  four-cylindered  air  engine 
and  has  a gear  on  the  shank  of  the  machine.  The  auger  is  attached  to  a small  chuck 
that  is  screwed  on  to  the  end  of  the  shank.  A hose  three-eighths  inch  in  diameter 
and  50  feet  long,  attached  to  the  conveyor  pipe,  furnishes  the  power  for  the  drill. 

The  complement  of  men  required  to  run  a block  is  13 — that  is,  block  boss,  machine 
runner  and  helper,  driller,  who  also  acts  as  shot  firer,  engine  boy,  head  man,  and 
six  loaders. 

The  “block  boss,”  or  leader  of  the  crew,  has  direct  charge  of  the  block.  He  must 
be  a man  who  has  some  knowledge  of  mining  and  the  care  of  machinery,  and  must 
possess  good  executive  ability.  The  balance  of  the  crew,  with  the  possible  excep- 
tion of  machine  men,  are  generally  non-English-speaking  men. 

In  preparation  for  the  day’s  work  the  machine  has  cut  one  rail  (30  feet)  on  the 
previous  afternoon.  In  the  morning  this  coal  is  shot  down  and  the  loaders  begin 
work  immediately.  It  requires  from  four  and  one-half  to  five  hours  for  the  machine 
men  to  finish  the  cut.  The  machine  is  then  overhauled  and  moved  up  in  position 
to  start  the  return  cut.  After  finishing  their  own  work  the  runner  and  his  helper  go 
back  on  the  block  and  make  preparations  for  the  moving  of  the  conveyor.  This 
consists  of  setting  a line  of  props,  called  the  line  row,  about  8 feet  apart,  and  a distance 
from  the  conveyor  equal  to  the  depth  of  the  undercut.  As  these  are  placed  the  old 
line  row,  which  is  now  against  the  conveyor,  is  withdrawn.  The  pulling  jacks  for 
moving  the  conveyor  are  distributed  along  the  block  40  feet  apart  and  placed  in 
position. 

The  shot  firer  keeps  closely  after  the  machine,  and  is  through  shooting  shortly 
after  the  undercut  is  finished.  He  then  starts  from  the  far  end  of  the  block  to  drill 
holes  in  the  new  face.  It  usually  takes  him  about  two  hours  daily  to  drill  the  entire 
width  of  the  block. 

Each  loader  is  supplied  with  a pick  and  shovel  and  a piece  of  sheet  iron  9 inches 
wide  and  6 feet  long,  which  he  attaches  to  the  conveyor  to  act  as  a side  board.  As 
each  loader  cleans  up  his  place  he  moves  forward  to  the  head  of  the  line.  This  con- 
tinues until  the  coal  is  loaded  out,  which  usually  requires  about  six  and  one-half 
hours, 


COAL  MINING. 


Ill 


When  cleaned  up  the  drive  is  reversed  and  the  timber,  which  has  arrived  on  the 
last  trip,  is  run  through  on  the  conveyor  to  such  points  on  the  block  where  it  is  re- 
quired. When  this  is  accomplished  the  power  is  shut  off  by  means  of  a valve  located 
at  the  top  of  the  block  heading.  The  hose  is  disconnected  from  the  main  feed  pipe 
and  the  conveyor  is  moved  up  to  the  line  row.  This  lateral  move  of  the  conveyor 
requires  very  little  time,  very  seldom  exceeding  five  minutes.  A break  row,  consist- 
ing of  two  rows  of  props  set  2 feet  apart,  is  now  placed  along  the  lower  side  of  the 
conveyor.  These  props  are  set  on  a cap  piece,  placed  on  a small  pile  of  slack,  and 
wedged  at  the  top.  Two  break  rows  are  all  that  is  necessary  to  protect  the  block. 
In  the  meantime  a portion  of  the  crew  are  engaged  in  pulling  out  the  extra  break 
row.  This  is  the  most  hazardous  work  on  the  block  and  is  given  personal  attention 
by  the  block  boss.  Axes  arfe  used  in  this  operation,  and  about  75  per  cent  of  the 
props  recovered  are  practically  uninjured. 

While  the  block  crew  are  employed  timbering  the  conveyor  man  and  hoist  boy 
make  the  necessary  pipe  connections  and  go  along  the  conveyor  with  a pump  jack 
and  level  it  up.  They  also  build  a crib  at  the  head  end,  which  is  placed  so  as  to 
prevent  the  roof  from  breaking  over  into  the  block  heading. 

When  the  timber  drawers  have  advanced  such  a distance  from  the  machine  that 
the  noise  of  the  exhaust  will  not  annoy  them,  the  machine  begins  cutting  and  is  usu- 
ally able  to  have  one  rail,  or  about  30  feet,  cut  before  the  shift  is  over. 

With  a 5-foot  undercut  the  block  throws  125  tons.  Four  cuts  a week  are  on  an 
average  obtained  from  each  block,  which  makes  a daily  average  of  100  tons. 

Although  the  results  obtained  from  this  system  of  mining  were  highly  satisfactory, 
it  was  found  there  was  still  room  for  improvement,  especially  with  regard  to  the 
original  cost  of  the  development  and  the  dead  work  connected  with  the  running  of 
the  block.  It  was  with  the  idea  of  remedying  these  features  and  of  improving  on 
other  less  important  conditions  that  the  triple-conveyor  system  was  designed  and 
installed.  After  being  in  use  for  over  a year  in  four  of  the  mines  where  electricity  is 
the  power  used  the  results  obtained  are  even  better  than  were  anticipated. 

In  laying  out  a mine  for  this  system  the  main  entry  and  airway  are  driven  up  or 
down  the  pitch,  and  cross  headings  are  driven  off  them  at  intervals  of  400  feet  at  such 
an  angle  as  will  give  a 2 per  cent  grade;  75-foot  barrier  pillars  are  left  on  each  side  of 
the  main  entries.  The  cross  heading  is  driven  20  feet  wide  and  gobbed  on  the  lower 
side.  The  air  course,  which  afterward  is  used  as  the  block  face,  is  driven  20  feet 
wide,  but  no  bottom  is  lifted;  a 40-foot  pillar  is  maintained.  Block  headings  are  run 
perpendicularly  off  the  cross  headings  at  518-foot  centers;  they  are  driven  18  feet 
wide,  with  bottom  lifted  in  the  center  5 feet  wide,  and  to  such  a depth  as  will  give 
a clearance  of  5 feet. 

When  the  block  is  ready  for  operation  a conveyor  350  feet  long  is  placed  in  the 
block  heading,  and  along  the  face  of  the  air  course  on  each  side  is  placed  a conveyor 
250  feet  long,  with  delivery  ends  directly  over  the  main  conveyor,  one  being  5 feet 
in  advance  of  the  other.  Each  conveyor  is  driven  by  a 20-horsepower  250- volt  series- 
wound  motor  incased  in  a sheet-iron  frame  mounted  on  steel  shoes,  so  as  to  be  easily 
moved. 

Airways  are  maintained  on  the  blocks  by  driving  two  places  slightly  in  advance  of 
the  block  face,  6 and  4 feet  wide,  respectively,  with  a 10-foot  pillar  between.  The 
first  place  acts  as  a stable  for  the  machine  and  is  driven  by  the  machine.  The  air- 
way is  pick-mined,  and  one  man  manages  to  keep  these  other  places  going  on  the  rear 
end  of  both  blocks.  By  this  arrangement  no  cribbing  is  necessary. 

The  blocks  are  worked  to  within  25  feet  of  the  cross  heading,  when  the  conveyors 
are  removed  to  another  block.  The  remaining  pillar  is  brought  back  along  with  the 
heading  stumps. 

The  power  is  carried  to  the  top  of  the  block  heading  by  a 2-0  wire.  Here  are  attached 
two  insulated  twin  cables,  one  to  furnish  power  to  the  machines,  the  other  for  the 
drives  and  hoist. 


112  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


The  cables  are  carried  down  the  block  heading,  one  on  each  side  of  the  main  con- 
veyor, being  attached  to  it  by  means  of  malleable-iron  brackets.  At  the  junction  of 
the  conveyors  connections  are  made  with  the  drives,  also  with  a cable  that  is  attached 
to  each  of  the  face  conveyors. 

Stations  are  established  50  feet  apart  on  the  face-conveyor  cables,  to  which  connec- 
tions are  made  with  the  short  cable  attached  to  the  long-wall  machines  and  electric 
drills.  Switches  are  placed  at  the  head  end  of  the  main  conveyor,  by  which  the  power 
is  controlled. 

The  method  of  handling  the  cars  to  the  conveyor  is  simple.  A side  track  is  laid  300 
feet  long,  of  which  the  block  heading  is  the  center.  Connection  is  made  with  the 
main  track  at  the  lower  end,  and  a crossover  switch  is  placed  directly  under  the 
conveyor.  At  the  upper  end  of  the  siding  is  placed  an  electric  hoist.  A trip  of  14 
cars  is  shoved  into  the  empty  track,  and  the  rope  is  attached  and  the  trip  pulled  up 
to  the  conveyor.  Signal  wires  are  hung  between  the  conveyor  and  the  hoist,  and  as 
each  car  is  loaded  the  trip  is  pulled  forward.  When  loaded  the  trip  is  dropped  on  the 
loaded  siding,  the  rope  disengaged  and  attached  to  the  empties. 

The  crew  operating  a double  block  consists  of  17  men — that  is,  block  boss,  machine 
runner  and  helper,  driller,  shooter,  two  conveyor  men,  hoist  boy,  five  loaders,  and 
four  timber  men. 

Two  long- wall  machines  are  used,  one  for  each  side,  although  one  machine  can 
keep  up  the  work  in  case  of  emergency. 

As  the  machine  men  finish  cutting  one  block  they  put  the  machine  in  position  to 
start  back  on  the  cut  and  move  over  to  the  next  block  and  begin  cutting.  They  are 
followed  by  the  shooter  and  loaders.  The  driller  sets  the  line  row  and  also  has  time 
to  assist  in  loading. 

When  a block  is  cleaned  up  the  timber  men  move  up  the  conveyor,  set  the  break 
rows,  pull  the  timber,  and  make  everything  ready  for  the  conveyor  to  start  when  the 
opposite  block  is  loaded  out. 

The  main  conveyor,  which  is  made  up  of  12-foot  sections,  is  disjointed  about  every 
third  day,  and  one  of  the  sections  taken  out  and  moved  to  the  block  heading  next  to 
be  worked.  The  surplus  length  of  cable  is  gathered  on  a reel  located  at  the  head  end 
of  the  main  conveyor. 

The  working  of  the  face  is  similar  to  that  of  the  single  block  with  the  exception  that 
the  machine  men,  loaders,  etc.,  continue  at  their  own  special  work  during  the  whole 
shift,  the  dead  work  being  taken  care  of  by  the  four  timber  men,  thus  not  hindering 
the  steady  flow  of  coal,  which  averages  150  tons  per  day. 

For  the  purpose  of  keeping  the  machinery  in  as  good  a shape  as  possible,  a skilled 
mechanic  is  attached  to  each  mine.  He  assumes  charge  in  case  of  an  accident  and 
makes  necessary  repairs,  although  most  of  the  breakdowns  are  easily  taken  care  of  by 
the  block  boss  and  machine  man. 

In  the  starting  of  a block  is  where  the  best  results  are  obtained,  as  the  roof  requires 
little  attention  until  about  100  feet  have  been  extracted.  It  then  begins  to  weigh 
heavy  on  the  posts,  and  it  is  found  necessary  to  carry  three  or  four  double  break  rows 
in  anticipation  of  what  is  called  the  “big  break.”  This  usually  occurs  when  the  block 
is  advanced  from  100  to  150  feet,  although  in  several  instances  a 500-foot  face  has  been 
carried  up  200  feet  before  the  overhanging  strata  broke.  After  the  sand  rock  is  down 
only  two  break  rows  are  carried,  and  the  roof  keeps  breaking  behind  the  last  row  as 
the  face  is  extended. 

The  men  are  paid  day  wages,  and  as  they  become  accustomed  to  the  work  and 
machinery  are  advanced  accordingly.  The  block  boss,  as  an  incentive  to  secure  the 
best  results,  is  paid  a small  bonus  per  ton  besides  his  regular  day  rate. 

The  cost  averages  for  the  last  two  years  show  that  block  coal  is  loaded  on  the  mine 
cars  35  per  cent  cheaper  than  the  district  mining  rate,  but  this  cost  can  be  materially 
reduced  when  a few  improvements  now  being  worked  out  are  brought  to  a state  of 
perfection . Among  these  may  be  mentioned  a more  simple  mechanical  rig  for  spotting 
the  mine  cars  and  a scheme  for  reducing  the  amount  of  timber  used. 


CLAY  AND  SHALE. 


113 


LITERATURE  ON  COAL  MINING. 

For  the  very  latest  information  and  statistical  data,  together  with 
brief  descriptions  of  the  conditions  of  mines,  improvements  made 
therein,  and  the  number  and  cause  of  accidents  by  years,  the  reader 
is  referred  to  the  annual  volume  entitled  “ Report  of  the  Department 
of  Mines,  Pennsylvania.”  Most  of  the  area  included  in  the  Johnstown 
quadrangle  was  in  the  sixth  bituminous  district  of  the  State  when 
this  report  was  written.  For  information  regarding  coal-mining 
methods  in  general  the  reader  is  referred  to  the  “Coal  and  metal 
miners’  pocket  book,”  ninth  edition,  1904,  pages  280  et  seq. 

CLAY  AND  SHALE. 

MODE  OF  TREATMENT. 

The  clay  materials  of  the  Johnstown  quadrangle  are  flint  clays, 
plastic  clays  (including  some  fire  clays),  and  shales. 

On  pages  14  to  28  of  this  bulletin  a detailed  description  is  given 
of  the  rocks  in  which  the  workable  or  potentially  workable  shale 
and  clay  beds  are  found,  and  to  these  preliminary  descriptions  the 
reader  is  referred  for  an  explanation  of  the  names  which  are  applied 
to  the  beds  containing  the  clays  and  which  are  employed  in  the  fol- 
lowing discussions.  The  treatment  of  the  clays,  like  that  of  the  coal, 
will  be  twofold,  consisting  of  (1)  a preliminary  description  of  their 
general  character  and  geologic  position,  followed  (2)  by  a detailed 
description  by  districts,  intended  for  the  use  of  those  who  are  more 
particularly  interested  in  the  subject.  The  detailed  descriptions  will 
be  accompanied  by  analyses  and  sections.  The  distribution  of  the 
clay  beds  which  are  regarded  as  of  economic  importance  is  shown  on 
Plate  I by  means  of  purple  lines. 

GENERAL  DESCRIPTION. 

FLINT  CLAYS. 

Flint  clays  occur  at  three  or  more  horizons  in  the  Johnstown  area. 
The  highest  is  in  the  Conemaugh  formation  and  ranges  in  position 
from  50  to  nearly  100  feet  above  the  Upper  Freeport  coal.  It  usually 
occurs  very  close  to  the  Mahoning  coal  in  the  hills  immediately  about 
Johnstown,  and  its  distance  above  the  Upper  Freeport  coal  is  there- 
fore nearer  50  to  75  feet  than  100  feet.  A clay  in  a similar  position 
with  respect  to  the  top  of  the  Allegheny  formation  was  also  observed 
in  the  hills  north  of  South  Fork.  It  appeared  to  be  of  the  ordinary 
plastic  variety.  In  the  Blacklick  Creek  district,  near  Wehrum,  a 
flint  clay  has  been  observed  at  many  places  in  a similar  position  with 
reference  to  the  Mahoning  sandstone  member.  This  flint  clay,  which 
69516°— Bull.  447—11 8 


114  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

in  many  places  attains  a thickness  of  7 feet,  is  probably  to  be  corre- 
lated with  the  flint  clay  occurring  near  Johnstown. 

In  the  Allegheny  formation  a flint  clay  was  observed  near  the 
northwest  edge  of  the  quadrangle,  in  the  valley  of  Mardis  Run.  It 
occurs  25  feet  below  the  Upper  Freeport  coal  and  probably  corre- 
sponds with  the  Bolivar  flint  clay  of  the  area  to  the  west. 

The  most  important  flint  clay  in  the  entire  quadrangle  is  that  occur- 
ring at  the  Mercer  horizon  in  the  hills  about  South  Fork,  where  it  is 
associated  with  plastic  clay.  In  the  mine  of  J.  H.  Wickes  it  is  4J 
feet  thick.  The  flinty  character  is  persistent  between  South  Fork  and 
Mineral  Point,  but  elsewhere  throughout  the  quadrangle  the  Mercer 
member  is  usually  characterized  by  a band  of  shale  and  plastic  clay. 

PLASTIC  CLAYS. 

Plastic  clays  have  been  observed  at  many  horizons  in  the  Johns- 
town quadrangle.  At  only  a few  places,  however,  are  their  position 
with  reference  to  transportation  facilities  and  their  thickness  such  as 
to  make  them  of  great  economic  importance.  A few  plastic-clay 
beds  have  been  observed  in  the  Conemaugh  formation.  Many  of 
the  coals  in  the  Allegheny  formation  are  underlain  by  plastic  clays. 
The  clay  below  the  Upper  Freeport  is  of  workable  thickness  at  some 
places.  Below  the  “cement  rock”  associated  with  the  Upper  Kit- 
tanning (Cement)  coal  a deposit  of  clay  was  noted  at  some  places 
around  Johnstown.  The  most  important  plastic  clay  in  the  Allegheny 
formation  is  that  below  the  Lower  Kittanning  (Miller  or  B)  coal 
bed,  and  it  is  extensively  mined  around  Johnstown  and  South  Fork 
in  connection  with  .that  coal.  It  is  mixed  with  the  flint  clay  from 
South  Fork  and  Dean  station  to  make  all  grades  of  fire  brick  and 
refractory  material  in  general.  This  clay  varies  in  thickness  from 
less  than  3 feet  to  12  feet,  of  which  from  to  5 feet  is  worked  in  the 
most  important  clay  mines  near  Johnstown.  At  Seward  12  feet  of 
clay  is  reported  below  the  Lower  Kittanning  coal,  but  of  this  thickness 
only  6 feet  is  mined  and  used  in  the  manufacture  of  buff  or  light- 
colored  brick. 

In  the  northern  part  of  the  quadrangle,  along  Blacklick  Creek  and 
at  Conemaugh  Furnace,  the  clay  below  the  Lower  Kittanning  coal  is 
of  workable  thickness,  and  there  is  no  reason  why  its  quality  should 
not  compare  with  that  of  the  plastic  clay  near  Johnstown  and  South 
Fork.  So  far  as  known,  however,  it  has  never  been  mined  in  con- 
nection with  the  coal  in  either  of  these  districts. 

The  lowest  plastic  clay  in  the  region  occurs  at  the  Mercer  horizon. 
This  clay  is  associated  with  and  occurs  immediately  above  the  flint 
clay  at  the  same  horizon  near  South  Fork.  Plastic  clay  of  Mercer 
age  is  also  found  on  Stony  Creek  in  the  hills  north  of  the  mouth  of 
Paint  Creek  and  farther  to  the  south.  It  is  also  present  in  the  hills 


CLAY  AND  SHALE. 


115 


north  of  Sheridan  and  is  worked  at  a quarry  in  this  locality.  The 
corresponding  clays  have  been  prospected  but  are  not  worked  at 
present  on  the  west  slope  of  Laurel  Ridge,  a few  miles  southeast  of 
Conemaugh  Furnace. 

SHALES. 

In  the  Johnstown  quadrangle  valuable  shale  beds  are  scattered 
through  the  Conemaugh  and  Allegheny  formations,  and  in  the  Potts- 
ville  formation  the  Mercer  member  is  nearly  everywhere  characterized 
by  the  presence  of  a shale  bed  of  varying  thickness.  Near  Johns- 
town valuable  shale  beds  occur  in  the  lower  300  feet  of  the  Cone- 
maugh formation  and  are  worked  near  the  city.  The  higher  beds  of 
the  Conemaugh  are  exposed  in  the  railroad  cuts  west  of  Wilmore,  and 
the  numerous  shale  beds  there  included  (see  section,  p.  16)  insure  the 
presence  of  much  good  brickmaking  material  admirably  situated 
with  respect  to  transportation.  At  the  Bruce  H.  Campbell  quarry, 
north  of  Sheridan,  a clay  that  is  associated  with  rounded  bowlders 
and  is  presumably  of  Pleistocene  age  is  worked  (PL  V,  B).  Residual 
clays  are  so  widely  distributed  in  this  quadrangle  as  hardly  to  merit 
detailed  mention. 

DESCRIPTION  BY  DISTRICTS 
JOHNSTOWN  DISTRICT. 

FLINT  CLAYS. 

Flint  clay  occurs  persistently  at  but  one  horizon  in  the  Johnstown 
district.  This  horizon  is  at  or  just  above  the  Mahoning  sandstone 
member  and  in  the  hills  surrounding  the  city  it  is  50  to  70  feet  above 
the  Upper  Freeport  (Coke  Yard)  coal.  Though  fairly  well  distrib- 
uted in  favorable  locations  for  easy  exploitation,  this  clay  is,  so  far 
as  known,  worked  only  by  the  Johnstown  Pressed  Brick  Company  at 
its  plant  on  a hill  east  of  the  city.  A section  of  the  rocks  in  the 
hill  will  show  the  position  of  this  clay  and  its  relation  to  the  under- 
lying coal,  which  is  at  the  top  of  the  Allegheny  formation. 

Section  of  lower  part  of  Conemaugh  formation  in  hill  east  of  Johnstown. 


Feet. 

Concealed,  and  sandstone  from  top  of  hill 91 

Shales 10 

Shales,  black 5 

Shales,  brick-red 40 

Concealed,  but  probably  shales 25 

Shales,  dull  olive,  weathering  reddish  « 25 

Shales,  olive  to  red 5 

Shales,  dark  olive  green,  slightly  gritty,  with  iron  oxide  and  man- 
ganese oxide  on  the  bedding  planes  « 13-15 

Sandstone,  laminated 15 

Shales 30 


a Beds  worked  for  brick  material. 


116  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Concealed,  but  with  a sandstone  in  its  upper  part. 
Flint  clay  fl 

Shales 

Shales,  ferruginous 

Shales,  green,  concretionary 

Shales,  irregularly  bedded 

Shales,  sandy 

Sandstone,  massive  (Mahoning) 

Concealed 

Coal,  3 feet  6 inches. . 


Bone,  5 inches. 


Upper  Freeport  (Coke  Yard)  coal 


Ft. 

42 

8 

10 

10 

5 

8 

25 

12 


3 11 


Fragments  of  flint  clay  have  been  seen  in  the  following  localities 
near  Johnstown : On  the  road  ascending  Shingle  Run,  in  Dale  Bor- 
ough, east  of  Johnstown,  more  than  2 feet  of  flint  clay  associated  with 
shale  was  measured  60  feet  above  the  Mahoning  sandstone  member. 
An  old  prospect  hole  on  this  flint  clay  was  seen  on  the  road  leading 
to  Grandview  Cemetery,  in  which  the  clay  was  about  65  feet  above 
the  Upper  Freeport  (Coke  Yard)  coal;  it  was  of  a light-straw  color 
and.  appeared  to  be  of  good  quality.  On  the  Ferndale-Johnstown 
road,  a short  distance  north  of  the  Eighth  Ward  mine  of  the  Citizens 
Coal  Company,  an  abundance  of  flinty  clay  debris  occurs  above  the 
road  near  the  top  of  the  massive  Mahoning  sandstone.  In  the  hill 
above  the  Baltimore  and  Ohio  Railroad  tunnel  east  of  Island  Park, 
on  the  new  county  road,  some  flint  clay  was  observed  about  40  feet 
above  the  Upper  Freeport  coal  and  near  the  top  of  the  Mahoning 
sandstone.  Northwest  of  Johnstown,  in  the  hills  bordering  Laurel 
Run  and  its  branches  on  the  east,  a short  distance  east  of  the  old 
coke  yard  from  which  the  Upper  Freeport  gets  its  local  name,  this 
flint  clay  is  exposed,  indicating  a probable  continuity  of  the  bed  as 
far  west  as  the  valley  of  Laurel  Run.  Here  again  the  flint  clay  is 
about  50  feet  above  the  Upper  Freeport  coal.  Northwest  of  Johns- 
town, on  the  road  ascending  Pleasant  Hill  from  the  valley  of  Cone- 
maugh  River,  a flint  clay  occurs  about  110  feet  above  the  Upper 
Freeport  coal  and  10  feet  below  a smaller  bed  of  coal.  This  smaller 
bed  of  coal  may  possibly  be  higher  stratigraphically  than  the  seam 
70  feet  above  the  Upper  Freeport  at  the  Baltimore  and  Ohio  Rail- 
road tunnel  near  Island  Park;  if  so,  the  flint  clay  of  Pleasant  Hill  is 
higher  than  that  previously  described,  and  there  are  two  flint-clay 
horizons  in  the  100  feet  at  the  base  of  the  Conemaugh  formation. 
At  the  southern  edge  of  the  quadrangle,  in  Somerset  County,  in  the 
hills  bordering  Stony  Creek,  this  same  flint  clay  has  been  observed. 

Should  the  clay  after  careful  prospecting  prove  to  be  present  in 
sufficient  quantity  and  of  such  quality  as  to  justify  its  exploitation 
at  the  above-named  localities,  it  could  be  marketed,  as  most  of  the 


o Beds  worked  for  brick  material. 


CLAY  AND  SHALE. 


117 


Occurences  which  have  been  noted  are  conveniently  situated  with 
respect  to  transportation.  Deposits  of  this  clay  too  far  removed 
from  market  and  transportation  to  have  commercial  value  have  also 
been  observed  on  the  headwaters  of  Mill  Creek  and  Dalton  Run. 

It  should  be  added  that  the  occurrences  noted  above  are  largely 
roadside  outcrops  at  which  it  is  impossible  to  determine  the  exact 
thickness  and  nature  of  the  clays.  Only  careful  prospecting  can 
determine  these  points,  but  the  fact  that  one  of  the  flint  clays  is 
being  exploited  at  one  locality  is  significant. 

PLASTIC  CLAY. 

The  flint  clay  above  the  Mahoning  sandstone  assumes  a plastic 
phase  at  places  in  the  Johnstown  district.  Most  of  the  valuable 
plastic  clay  in  this  region,  however,  occurs  in  the  Allegheny  forma- 
tion (“Lower  Productive  Coal  Measures”).  At  a few  places  a clay 
bed  of  workable  thickness  occurs  below  the  Upper  Freeport  coal,  in 
connection  with  which  it  might  be  mined.  At  the  Cyrus  Shepard 
mine,  leased  by  L.  J.  Mitchell,  east  of  Franklin  and  near  the  mouth 
of  Clapboard  Run,  2 feet  4J  inches  of  clay  were  measured  by  Mr. 
Martin,  but  the  clay  is  known  not  to  be  persistent,  as  but  a short 
distance  away  the  section  obtained  shows  an  entirely  different  aspect. 

A clay  bed  underlies  the  Johnstown  limestone  member — that  is, 
the  limestone  occurring  near  or  just  below  the  base  of  the  Upper 
Kittanning  (Cement)  coal.  This  clay  has  been  worked,  but  it  is  not 
now  exploited.  It  is  referred  to  in  the  report  on  this  district  by 
F.  Platt  and  W.  G.  Platt®  as  having  been  developed  by  Mr.  Haws, 
of  Johnstown.  The  clay  was  analyzed  by  T.  T.  Morrell,®  with  the 
following  results : 

Analysis  of  clay  occurring  below  the  Johnstown  limestone  member. 


Silica  (Si02) 71.98 

Alumina  (A1203) 26.29 

Ferric  oxide  (Fe203) 2.  21 

Magnesia  (MgO) 44 

Manganese  dioxide  (Mn02) 32 


101.  24 

The  most  valuable  clay  in  the  Allegheny  formation  is  that  under- 
lying the  Lower  Kittanning  (Miller)  coal.  Many  of  the  mines  work- 
ing this  coal  around  Johnstown  produce  also  considerable  amounts 
of  the  clay.  The  clay  bed  in  this  district  ranges  from  less  than  3 to 
about  6 feet  in  thickness,  but  locally  it  may  be  even  thicker  ttuin  this. 
It  usually  underlies  the  lower  bench  of  the  Lower  Kittanning  coal, 
from  which  it  is  separated  by  a few  inches  of  shale ; or,  in  the  absence 


a Second  Geol.  Survey  Pennsylvania,  Rept.  H2, 1875,  p.  148. 


118  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


of  the  lower  bench,  it  occurs  below  the  main  coal  itself,  separated 
from  it  by  about  3 to  4 inches  of  bone  or  shale.  It  is  a light-drab 
clay,  not  very  hard,  of  irregular  fracture,  greasy  to  the  touch,  and 
slakes  on  exposure  to  the  weather.  Its  composition  is  indicated  by 
the  following  analyses: 


Analyses  of  clay  underlying  the  Miller  seam. 


1. 

2. 

3. 

4. 

Silica  (Si02) 

65. 90 
20. 30 
a 1.60 
.66 
.09 
.34 
2. 98 
1.20 
6.  50 

66.  40 
19. 80 
a 1.68 
.61 
.10 
.30 
3. 24 
1.00 
6.  40 

53. 10 
27. 80 
a 3. 08 
.60 
.22 
.48 
3.  58 
1.20 
10.  20 

68.82 
20.85 
2.  79 
.23 
.82 

Alumina  (AI2O3) 

Ferric  oxide  (Fe2C>3) 

Magnesia  (MgO) 

Lime  (CaO). 

Soda  (Na20) 

Potash  (K2O) ■ 

Titanium  oxide  (Ti02)... 

MnC>2  . 66 
5.83 

Loss  on  ignition 

99.57 

99.  53 

100. 26 

100.00 

a Total  iron  calculated  as  F«203. 

1.  Citizens’  Coal  Company’s  Green  Hill  mine.  Johnstown;  E.  C.  Sullivan,  analyst. 

2.  A.  J.  Haws  & Sons  (Limited)  mine,  near  the  stone  bridge,  Johnstown;  E.  C.  Sullivan,  analyst. 

3.  Seward  Coal  Company’s  mine,  Seward,  Westmoreland  County,  Pa.;  E.  C.  Sullivan,  analyst. 

4.  Clay  underlying  the  Lower  Kittanning  (Miller)  seam  at  Johnstown;  T.  T.  Morrell,  analyst.  Second 
Geol.  Survey  Pennsylvania,  Rept.  H2,  p.  148. 

This  clay  is  worked  about  Johnstown  by  W.  J.  Williams  at  Kern- 
ville.  Below  the  coal  at  the  Kernville  mine  there  is  a shale  layer 
of  varying  thickness,  about  2 to  6 inches  in  places,  below  which  is 
from  3 to  5 feet  of  plastic  clay.  This  clay  is  mined  and  used  at  one 
of  the  local  brickyards.  At  the  Green  Hill  mine  of  the  Citizens’  Coal 
Company  the  average  thickness  of  the  underlying  clay  is  5 feet.  This 
also  is  shipped  to  a local  brick  plant.  This  clay  is  mined  by  A.  J. 
Haws  & Sons  (Limited),  both  at  their  shaft  near  the  famous  stone 
bridge  in  Johnstown  and  to  the  west  at  Coopersdale.  In  the  shaft 
workings  an  average  of  nearly  3 feet  is  worked.  At  Coopersdale  it 
averages  3J  feet  in  thickness  but  in  places  runs  as  thick  as  5 feet. 
It  was  observed  in  the  mine  that  when  the  clay  attained  its  maximum 
thickness  the  coal  appeared  in  a single  bench,  with  its  lower  4 or  5 
inches  bony.  At  both  the  Haws  mines  the  Lower  Kittanning  coal  is 
mined  with  the  clay,  and  is  used  as  the  fuel  to  burn  the  brick  at  the 
brick  plants  situated  at  the  mine  mouths.  The  clay  is  also  mined 
by  Robertson  & Griffith  on  St.  Clair  Run  in  connection  with  the 
overlying  coal. 

Nearly  all  the  product  of  the  Johnstown  clay  mines  is  used  at 
local  brick  plants,  where  it  is  mixed  with  flint  clay  from  the  Mercer 
horizon,  shipped  chiefly  from  South  Fork  and  Dean  station.  When 
thus  mixed  with  the  flint  clay  it  forms  a suitable  bond  in  a product 
that  is  used  in  the  manufacture  of  high-grade  refractory  products 
and  bricks  for  blast-furnace  and  open-hearth  work,  and  in  making 
sleeves,  nozzles,  tuyeres,  and  other  articles  exposed  to  high  tempera- 
tures. In  the  most  refractory  products  nothing  but  flint  clay  is  used. 


CLAY  AND  SHALE. 


119 


The  lowest  plastic  clay  in  the  Johnstown  quadrangle  is  associated 
with  the  Mercer  coal  and  is  not  exposed  immediately  about  the  city. 
In  the  hills  lying  east  of  Stony  Creek,  south  of  Kring,  on  the  Balti- 
more and  Ohio  Railroad,  this  horizon  has  been  prospected  and  some 
clay  and  shale  have  been  found,  but  they  have  never  been  worked. 
At  one  exposure  of  the  Mercer  south  of  the  quadrangle,  on  the  west 
flank  of  the  Ebensburg  anticlinal  axis,  more  than  11  feet  of  clays 
and  shales  were  measured  in  one  exposure.  Flint  clay  was  not 
observed  in  connection  with  the  Mercer  at  any  of  the  old  prospect 
pits. 

North  of  Sheridan,  at  the  quarry  of  Bruce  H.  Campbell,  the  fol- 
lowing section  was  measured,  showing  6 feet  and  possibly  more  of 
clay  below  the  Mercer  coal: 

Section  of  Mercer  shale  member  at  Bruce  H.  Cam/pbell  quarry , north  of  Sheridan. 

Sandstone  in  massive  bowlders.  Ft.  in. 

Clay,  red,  with  rounded  bowlders  (Pleistocene?).  5-10 


Shales * 20 

Coal  and  bone 1 3 

Clay 6 

Shales 6 


That  the  underlying  clay  and  shales  are  much  thicker  than  is 
indicated  by  the  above  section  has  been  proved  by  sinking  three 
test  holes.  Both  red  and  buff  building  bricks  are  made  from  the 
clays  and  shale  quarried  here. 

SHALES. 

It  has  been  remarked  that  the  most  important  shale  horizons 
about  Johnstown  are  confined  to  the  lower  300  feet  of  the  Conemaugh 
formation.  The  section  given  on  pages  115-116  shows  the  character 
of  the  lower  400  feet  of  beds  in  this  group  of  rocks  in  a hill  east  of 
the  city.  From  about  50  feet  above  the  top  of  the  Upper  Freeport 
(Coke  Yard)  coal  to  the  top  of  the  hill  numerous  promising  beds  of 
shale  are  exposed.  Most  of  the  shale  group  lying  between  165  and 
210  feet  above  the  Upper  Freeport  coal  is  being  worked  by  the 
Johnstown  Pressed  Brick  Company  into  a good  building  brick  of 
both  the  buff  and  red  varieties.  The  fuel  used  in  burning  the  brick 
is  obtained  from  the  Upper  Freeport  coal,  which  the  company  works 
in  the  same  hill.  The  shales  are  ground  through  a 12-mesh  sieve, 
or  to  a size  to  make  them  “ball.”  The  material  is  then  hoisted  by 
a bucket-belt  conveyor  to  the  sieve,  thence  sent  through  a hopper 
to  the  pans,  after  which  it  is  pressed  into  brick,  the  dry-press  process 
being  used. 

The  composition  of  the  shales  employed  is  indicated  below.  The 
shales  were  first  air  dried  and  then  subjected  to  the  usual  fusion,  with 
subsequent  analyses. 


120  MINERAL  RESOURCES  OF  JOHNSTOWN,  FA.,  AND  VICINITY. 


Ultimate  and  rational  analyses  of  shales  from  hill  east  of  Johnstown. 


1. 

2. 

Silica  (Si02) 

Alumina  ( A1203) 

Ferric  oxide  (Fe203) 

51.32 
24.39 

6. 94 
.14 
.70 
1.73 
Trace. 
1.43 
.23 
1.09 
.92 

11.32 

64.29 
17. 95 
5.  74 
Trace. 
.46 
1.30 
Trace. 
1.64 
.35 
1.80 
.95 
5. 44 

Manganese  oxide  (MnO) 

Lime  (CaO) 

Magnesia  (MgO) 

Sulphuric  anhydride  (SO3) 

Ferrous  oxide  (FeO) 

f(Na20) 

Alkahesj  * ' . 

Water  at  100°  C 

Ignition  loss 

Free  silica 

100.21  | 

99. 92 

10.09 

81.51 

8.40 

28.  54 
57. 85 
13. 61 

Clay  substance 

Feldspathic  substance 

100.00 

100.00 

1.  Sample  collected  from  upper  shale  bed:  see  sectioa  (p.  115).  Analysis  made  at  the  structural-mate- 
rials laboratory  of  the  United  States  Geological  Survey  at  St.  Louis.  A.  J.  Phillips,  analyst. 

2.  Sample  collected  from  lower  shale  bed;  see  section  (p.  115).  Analysis  made  at  the  structural-mate- 
rials  laboratory  of  the  United  States  Geological  Survey  at  St.  Louis.  P.  H.  Bates,  analyst. 

* 

In  Prospect  Hill,  north  of  Johnstown,  the  Cambria  Steel  Company 
has  quarried  shale  lying  about  80  to  100  feet  above  the  Upper  Freeport 
coal  and  utilized  it  in  connection  with  the  overlying  surface  clay  in 
the  manufacture  of  red  building  brick  of  good  quality.  The  brick 
plant  of  the  company  is  located  at  Cambria. 

The  geologic  structure  immediately  near  Johnstown  is  such  that 
the  beds  lie  fairly  flat  and  the  lower  few  hundred  feet  of  the  Cone- 
maugh  formation  is  exposed.  Sections  obtained  in  the  hills  around 
the  city  and  along  the  Pennsylvania  Railroad  to  the  west  indicate 
that  the  lower  part  of  this  formation  is  of  prevailingly  shaly  charac- 
ter, comparable  with  that  seen  in  the  hill  to  the  east.  It  is  therefore 
probable  that  a great  deal  of  brickmaking  material  exists  in  these 
hills  which  has  never  been  tested.  Though  all  this  shale  may  not  be 
of  the  grade  of  that  worked  by  the  Johnstown  Pressed  Brick  Com- 
pany, some  of  it  probably  is,  and  much  of  it  may  be  suitable  for 
paving  brick,  sewer  pipe,  fireproofing  of  various  sorts,  and  other 
rough  material.  All  the  shale  in  the  hills  about  the  city  and  to  the 
west  is  fairly  accessible  to  transportation,  and  cheap  fuel  is  assured 
by  the  presence  of  valuable  coal  beds  300  feet  or  more  below. 

The  lowest  promising  shale  horizon  in  this  district  is  associated 
with  the  Mercer  coal.  The  prospect  pits  on  the  Baltimore  and  Ohio 
Railroad  south  of  Kring  show  the  presence  of  dark  shales  at  this 
horizon.  At  points  north  of  Sheridan  the  Mercer  shale  is  thick  and 
is  worked  in  connection  with  the  overlying  Pleistocene  clays  at  the 
quarry  of  Bruce  H.  Campbell.  (See  PI.  Y,  B,  p.  28.)  The  section 
on  page  119  shows  20  feet  of  shales  overlying  the  coal,  and  the  thick- 
ness of  brickmaking  material  at  the  base  of  the  section  is  known  from 
test  holes  put  down  by  the  company  to  be  much  greater.  The  shales 
in  the  20-foot  bed  given  near  the  top  of  the  section  are  dark  brown 


CLAY  AND  SHALE. 


121 


and  drab  in  color,  somewhat  sandy,  and  concretionary.  This  shale 
is  mixed  with  the  overlying  clay,  and  the  mixture  is  used  in  making 
a buff  or  red  building  brick,  the  color  depending  on  the  proportions 
of  shale  and  clay  used.  The  beds  worked  at  this  quarry  rise  abruptly 
toward  the  west  at  a rate  that  soon  carries  the  Mercer  horizon  with 
its  shales  over  the  tops  of  the  hills. 

Mr.  Martin  collected  a sample  of  the  shale  from  this  quarry,  taking 
it  from  the  entire  width  of  the  exposure  and  then  mixing  it  with  the 
overlying  clay  in  the  proportion  of  2 parts  of  shale  to  1 of  clay.  The 
sample  was  analyzed  by  P.  II.  Bates,  of  the  structural-materials  labo- 
ratory of  the  Survey  at  St.  Louis,  with  the  following  results: 


Ultimate  and  rational  analyses  of  shale  and  clay  from  Mercer  shale  member,  B.  II.  Campbell 

quarry,  north  of  Sheridan. 


Silica  (Si02) 

Alumina  ( A1203) 

Ferric  oxide  (Fe203) 

Manganese  oxide  (MnO)  — 

Lime  (CaO) 

Magnesia  (MgO) 

Sulphuric  anhydride  (S03). 

Alkalies  |^a^' 

1k2o 


Water  at  100°  C 
Ignition  loss 


62.  86 
18.  85 
5. 19 
.37 
1.42 
.98 
. 11 
.06 
2.  59 
2.  27 
5.  45 


100. 15 


Free  silica 27.70 

Clay  substance 56.41 

Feldspathic  substance 15.  89 


SOUTH  FORK  DISTRICT. 


100.  00 


FLINT  CLAY. 

A band  of  clay  that  occurs  in  the  Pottsville  formation  in  the  South 
Fork  district  has  been  worked  at  points  south  of  the  Pennsylvania 
Railroad  from  South  Fork  westward  beyond  Mineral  Point  and  also 
at  a few  places  north  of  the  railroad.  In  this  district  this  clay  is 
characterized  by  a persistent  flinty  streak.  This  clay  is  present  in 
the  hills  along  Conemaugh  River  in  an  area  extending  west  to  about 
1 mile  east  of  Conemaugh  station.  The  outcrop  is  continuous  except 
where  the  local  dips  and  change  in  direction  of  the  river  carry  it  below 
drainage.  The  flinty  clay  may  not  be  present  at  all  points  between 
Mineral  Point  and  Conemaugh.  For  example,  the  clay  observed  at 
this  horizon  in  the  tunnel  of  the  old  Portage  Railroad  is  not  particu- 
larly flinty  in  character.  From  Mineral  Point  to  South  Fork,  how- 
ever, the  flinty  character  is  persistent. 

This  flint  clay  is  now  worked  by  the  Garfield  Fire  Clay  Company 
near  the  viaduct  and  by  J.  H.  Wickes  and  the  South  Fork  Fire  Brick 


122  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

Company  west  of  South  Fork.  The  following  section  was  measured 
at  Mr.  Wickes’s  mine: 


Section  of  fire  clay  at  J.  II.  Wickes’s  mine , South  Fork. 


Heavy  sandstone  roof.  Ft.  in. 

Clay,  plastic 3 6 

Coal f-2 

Clay,  flint 4 6 

Sandstone. 


This  clay  was  also  worked  by  the  Page-Reigard  Mining  Company 
near  Mineral  Point  and  at  South  Fork,  but  in  July,  1904,  the  mine  at 
South  Fork  was  shut  down.  It  is  reported  that  the  plastic  clay  is 
persistent  but  that  the  thickness  of  the  flint  clay  is  variable,  dwin- 
dling to  14  inches  in  a northeast-southwest  zone.  A specimen  of  the 
clay  was  collected  in  October,  1906,  and  analyzed  by  A.  J.  Phillips  at 
the  structural-materials  laboratory  of  the  United  States  Geological 
Survey  at  St.  Louis.  This  analysis  (No.  1 in  the  table  below)  may  be 
compared  with  an  analysis  of  what  is  believed  to  be  clay  from  the 
Mercer,  taken  from  the  central  band  of  the  bed  worked  years  ago  near 
the  viaduct.  This  latter  clay  was  not  definitely  fixed  in  its  strati- 
graphic relations  by  the  Platts.0  It  was  regarded  by  them  as  clearly 
underlying  all  the  workable  coals  and  as  being  connected  with  the 
“Conglomerate  Rock,”  as  the  Pottsville  was  sometimes  called,  and 
as  being  the  equivalent  of  the  fire  clay  of  Sandy  Ridge,  which  is  known 
to  be  in  the  Mercer  member.  The  third  analysis  in  the  table  repre- 
sents clay  from  the  middle  layer  in  the  Sandy  Ridge  bed. 


Ultimate  and  rational  analyses  of  Mercer  clays. 


1. 

2. 

3. 

Silica  (Si02) 

44.30 

38.31 
1.  40 

. 10 
.82 
.59 
Trace. 
.71 
.22 
.17 
.75 
12.77 

45.42 
36.  80 
b 3.  33 
d . 48 
.87 
. 45 

44.  950 
37.  750 
c 2.  700 

Alumina  ( AI2O3) 

Ferric  oxide  (Fe2C>3) 

Manganese  oxide  (MnO) 

Lime  (CaO) 

.302 

.216 

Magnesia  (MgO) 

Sulphuric  anhydride  (SOs) 

Ferrous  oxide 

.985 

Alkalies|K2Q 

} 

Water  at  100°  C 

Ignition  loss 

« 12.  65 

« 13.  050 

Free  alumina 

100. 14 

100.  00 

99.  953 

3.88 
93.  26 
2.86 

Clay  substance 

Feldspathic  substance 

100.  00 

a Second  Geol.  Survey  Pennsylvania,  Rept.  H2,  1875,  p.  146. 
b All  iron  reported  as  peroxide  of  iron. 
c Reported  “oxide  of  iron.” 
d Calculated  as  Mn02. 

« Reported  as  water  and  organic  matter. 

1.  Flint  clay  from  Mercer  horizon,  A.  J.  Wickes’s  mine,  South  Fork;  A.  J.  Phillips,  analyst. 

Flint  clay  from  Mercer  horizon,  near  the  viaduct;  T.  T.  Morrell,  dnalyst,  Second  Geol.  Survey  Pennsyl- 
vania, Rept  H2, 1875,  p.  147. 

3.  Fire  clay  of  Sandy  Ridge;  A.  S.  McCreath,  analyst,  Second  Geol.  Survey  Pennsvlvania,  Rept.  H, 
1874,  p.  119. 


CLAY  AMt)  SHALE. 


123 


There  is  a striking  similarity  among  these  analyses. 

At  South  Fork  the  clay  is  smooth,  hard,  compact,  light  to  dark 
gray  in  color,  breaks  with  a conchoidal  fracture,  and  burns  to  a 
straw-yellow  color.  The  analysis  indicates  a high-grade  material, 
with  perhaps  a little  too  much  iron. 

The  clay  mined  at  South  Fork  is  in  part  shipped  to  Johnstown 
and  in  part  mixed  with  plastic  clay  from  the  Lower  Kittanning  seam 
and  used  at  the  local  brick  plant.  Some  of  the  products  of  this  flint 
clay  have  been  tested  for  refractoriness  at  the  plant  of  the  Cambria 
Steel  Company  at  Johnstown  and  have  proved  highly  satisfactory. 

PLASTIC  CLAY. 

About  South  Fork  a plastic  clay  of  doubtful  value  has  been  ob- 
served at  a few  places  near  the  top  of  the  Mahoning  sandstone;  its 
position  corresponds  with  that  of  the  band  of  flint  clay  in  the  Johns- 
town district.  The  clay  below  the  Upper  Freeport  (Lemon)  coal  bed 
is  fairly  thick  in  this  region,  but  it  is  not  worked  at  present.  At 
O.  M.  Stineman’s  mine  No.  3 this  coal  is  underlain  by  2 feet  3 inches 
of  clay,  which  may  be  worked  at  some  future  time  in  connection 
with  the  coal.  This  clay  is  not  comparable  in  thickness  with  that 
which  directly  underlies  the  Lower  Kittanning  (Miller)  coal  seam, 
and  which  about  South  Fork,  as  near  Johnstown,  is  the  most  impor- 
tant plastic  clay  in  the  Allegheny  formation.  The  plastic  clay  asso- 
ciated with  the  Lower  Kittanning  coal  seam  is  usually  workable,  at 
some  places  having  a thickness  of  6 to  8 feet  and  averaging  about 
3 to  4 feet  of  workable  clay  of  good  grade.  A brief  note  on  the 
character  of  this  clay  will  be  found  in  the  description  of  its  occur- 
rence in  the  Johnstown  district  (p.  117),  where  analyses  also  are  given. 
There  is  every  reason  to  suppose  that  in  this  district  it  is  of  the  same 
quality  as  about  Johnstown.  Most  of  the  South  Fork  clay  is  mined 
in  connection  with  the  coal  and  is  used  almost  entirely  at  the  local 
brick  plant. 

SHALE. 

So  far  as  known  the  shales  in  the  South  Fork  district  have  not 
been  utilized.  In  the  two  large  cuts  west  of  the  town  of  Wilmore, 
on  the  main  line  of  the  Pennsylvania  Railroad,  shale  beds  are  exposed' 
that  vary  in  position  from  400  to  675  feet  above  the  Upper  Freeport 
coal.  In  the  surrounding  hills  many  promising  shales  are  found 
conveniently  situated  with  respect  to  transportation.  Their  appear- 
ance indicates  that  they  may  be  adapted  to  the  manufacture  of 
paving  brick  and  other  materials  that  require  only  an  inferior  grade 
of  clay  or  shale ; to  determine  their  fitness  for  any  purpose,  however, 
practical  tests  must  be  made.  In  a recent  cut  opposite  Ehrenfeld, 
along  the  new  county  road,  a bed  of  shale  50  to  60  feet  thick,  lying 
60  feet  above  the  Upper  Freeport  coal,  also  appears  to  be  promising. 


124  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

BLACKLICK  CREEK  DISTRICT. 

The  South  Branch  of  Blacklick  Creek  flows  along  the  northern  edge 
of  the  Johnstown  quadrangle.  It  is  joined  by  the  north  branch  a 
short  distance  west  of  Yintondale,  and  the  main  stream  flows  west- 
ward beyond  the  limits  of  the  area.  Deposits  of  flint  and  plastic" 
clay  are  found  in  the  adjacent  hills  along  the  creek,  and  although 
many  of  these  are  conveniently  situated  with  respect  to  lines  of 
transportation  the  demand  has  not  yet  been  sufficient  to  justify 
their  exploitation. 

FLINT  CLAY. 

The  flint  clay  in  the  Blacklick  Creek  district  occurs  at  two  horizons. 
The  higher  is  found  in  the  lower  part  of  the  Conemaugh  formation, 
above  what  is  thought  to  be  the  equivalent  of  the  Mahoning  sandstone 
member  and  a few  feet  below  a small  coal  bed,  possibly  the  Mahon- 
ing coal.  This  flint  clay  has  been  observed  in  many  places  north, 
west,  and  south  of  Wehrum,  but  the  rise  of  the  beds  toward  the  east 
causes  a gradual  increase  in  its  distance  from  the  valley  and  from 
transportation  facilities  and  finally  its  complete  absence  from  the 
hills.  West  of  Wehrum,  however,  both  north  and  south  of  Blacklick 
Creek,  it  occurs  at  many  points,  having  in  places  the  unusual  thick- 
ness of  7 to  8 feet.  It  is  a typical  flint  clay  in  appearance,  though 
its  content  of  iron  oxide  is  apparently  very  high.  A sample  col- 
lected from  a roadside  exposure  west  of  Dilltown  gave  the  following 
analysis : 

Partial  analysis  of  flint  clay  from  a natural  exposure  west  of  Dilltown. 

[E.  C.  Sullivan,  analyst.] 


Silica  (Si02) 50.3 

Alumina  (A1203) 21.3 

Ferric  oxide  (Fe203  )a 10.  4 

Magnesia  (MgO) 61 

Lime  (CaO) 39 

Soda  (Na20) 18 

Potash  (K,0) 1.14 

Titanium  oxide  (Ti02) 90 

Loss  on  ignition 12.  00 


97.22 

The  percentage  of  fluxing  materials,  principally  iron  oxide,  indicated 
in  this  analysis,  is  so  high  as  to  prohibit  its  practical  use.  A lower 
flint  clay,  lying  a few  feet  below  what  may  prove  to  be  the  Upper 
Freeport  coal,  was  seen  at  a few  places  in  the  valley  of  Mardis  Run, 
near  the  northwestern  edge  of  the  quadrangle.  This  clay  may  corre- 
spond to  the  Bolivar  clay  of  the  region  to  the  southwest.  Two  feet 
of  clay  was  seen  at  one  point  on  the  outcrop  and  the  bed  may  possibly 
be  thicker.  This  clay  is  rather  remote  from  transportation. 


a Total  iron  calculated  as  FejOg. 


CLAY  AND  SHALE. 


125 


PLASTIC  CLAY. 

The  coal  that  is  being  extensively  worked  in  the  valley  of  Blacklick 
Creek  is  regarded  as  the  equivalent  of  the  Lower  Kittanning  (Miller 
or  B)  seam  of  the  Johnstown  and  South  Fork  districts.  In  the  Black- 
lick  Creek  district,  as  well  as  along  Conemaugh  River,  this  coal  is 
‘Underlain  by  a promising  clay  bed.  This  clay  is  not  exploited  at 
present,  and  no  certain  measurement  of  its  thickness  was  obtained. 
At  many  of  the  mines  2 feet  or  more  of  promising  clay  was  seen, 
comparable,  in  appearance  at  least,  with  that  in  the  Johnstown 
district. 

MISCELLANEOUS  LOCALITIES. 


Along  the  western  flank  of  Laurel  Ridge,  near  the  line  of  the  Penn- 
sylvania Railroad,  the  Lower  Kittanning  (Miller)  coal  has  been 
opened  at  a few  places  and  the  clay  underlying  it  found  to  be  of 
workable  thickness.  At  the  coal  mine  of  the  Johnstown  Coal  Com- 
pany more  than  2 feet  of  clay  was  seen;  and  near  Seward,  beyond 
the  western  limits  of  the  quadrangle,  12  feet  of  clay  occurs  in  the 
same  position,  6 feet  of  which  is  worked  by  the  Seward  Brick  Com- 
pany.® 

About  2 miles  southeast  of  Conemaugh  Furnace,  on  the  main  line 
of  the  Pennsylvania  Railroad  and  south  of  it,  the  Conemaugh  Stone 
Company  has  done  considerable  quarrying  in  the  Pottsville  and  has 
exposed  the  Mercer  shale  member.  The  following  section  was 
measured  but  does  not  show  the  complete  thickness  of  the  clay: 


Section  showing  Mercer  shale  member  and  accompanying  clays  at  quarry  of  Conemaugh 

Stone  Company. 


Ft.  in. 


Shale,  dark,  with  2 inches  of  bone  near  base 3 

Fire  clay 1 

Clay,  sandy 1 

Clay,  good,  drab 1 

Coal  or  smut 

Clay,  drab 5+ 


PRODUCTION. 


The  firms  named  below  are  engaged  in  the  brick  and  clay  industry 
in  this  area.  In  addition  coal  companies  mining  the  Lower  Kittan- 
ning coal  about  Johnstown  and  South  Fork  may  produce  small 
quantities  of  the  underlying  clay  for  use  in  the  local  brick  plants. 
Clay  miners: 

Page-Reigard  Mining  Company,  flint  clay,  Mineral  Point. 

W.  J.  Williams,  plastic  clay,  Kernville. 

Citizens’  Coal  Company,  plastic  clay,  Green  Hill  mine,  Johnstown. 

Robertson  & Griffith,  plastic  clay,  St.  Clair  Run,  Morrellville. 


a For  an  analysis  of  the  clay  underlying  the  coal  mined  at  Seward,  see  p.  118. 


126  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 
Manufacturers  of  fire  brick: 

A.  J.  Haws  & Sons  (Limited),  Johnstown  and  Coopersdale. 

Hiram  Swank  Sons,  Johnstown. 

South  Fork  Fire  Brick  Company,  South  Fork. 

Manufacturers  of  building  brick: 

Cambria  Steel  Company,  Johnstown. 

Bruce  H.  Campbell  Brick  Company,  Sheridan. 

Johnstown  Pressed  Brick  Company,  Johnstown. 

BRICK  INDUSTRY. 

The  brick  industry  in  the  vicinity  of  Johnstown  has  grown  to 
considerable  magnitude.  Some  of  the  flint  clay  used  in  the  manufac- 
ture of  the  fire  brick  and  other  more  refractory  products  is  shipped 
from  other  parts  of  the  State,  but  except  for  this  most  of  the  raw 
material  used  is  of  local  occurrence. 

LIMESTONE  AND  CEMENT  MATERIALS. 

EXTENT. 

In  the  Conemaugh  formation  of  western  Pennsylvania  numerous 
limestone  members  have  been  found  and  traced  with  certainty  over 
broad  areas.  These  have  been  proved  to  be  so  constant  in  their  posi- 
tion in  the  geologic  column  that  they  have  been  named  and  have 
served  as  guides  in  unraveling  the  stratigraphy.  Some  of  these  are 
the  Pittsburg,  Clarksburg,  Elk  Lick,  Ames  or  “Crinoidal,”  and 
Upper  and  Lower  Cambridge  limestone  members  of  the  Allegheny 
Valley,  and  the  Johnstown  iron-ore  bed,  which  is  in  places  nothing 
more  than  a ferruginous  limestone  at  an  inconsiderable  distance 
from  the  outcrop.  Some  of  these  limestones  undoubtedly  occur  in 
the  Johnstown  quadrangle.  Actual  correlation  has  not  been  made, 
however,  partly  because  the  limestones  in  the  quadrangle  are  regarded 
as  lenticular  and  partly  because  they  are  so  numerous  that  they  can 
not  be  correlated  certainly  with  the  persistent  and  characteristic 
limestones  of  the  Allegheny  Valley. 

The  limestones  of  the  Conemaugh  are  of  no  importance  whatever 
commercially  and  have  never  been  used  except  for  fertilizing  pur- 
poses on  a very  small  scale.  The  limestones  in  the  Allegheny  are  of 
greater  importance  than  those  in  the  Conemaugh.  They  are  three 
in  number — the  Upper  Freeport  limestone  member,  the  Lower  Free- 
port limestone  member,  and  the  Johnstown  limestone  member. 

UPPER  FREEPORT  LIMESTONE  MEMBER. 

The  Upper  Freeport  limestone  member  appears  in  the  section  only 
near  South  Fork  and  Ehrenfeld.  A short  distance  east  of  Ehrenfeld 
it  is  exposed  in  some  recent  excavations  along  the  main  line  of  the 
Pennsylvania  Railroad.  It  is  a gray  limestone  from  1J  to  3 feet  in 


LIMESTONE  AND  CEMENT  MATERIALS.  127 

thickness  and  at  Ehrenfeld  it  is  very  irregularly  bedded.  It  lies  a 
short  distance  below  the  Upper  Freeport  coal,  being  separated  from 
it  by  about  2 feet  of  clay  containing  limestone  nodules  in  its  lower 
foot.  So  far  as  known,  this  particular  limestone  has  never  been  used 
in  this  area. 

LOWER  FREEPORT  LIMESTONE  MEMBER. 

The  Lower  Freeport  limestone  member  occurs  either  directly 
below  or  within  a foot  of  the  base  of  the  Lower  Freeport  coal,  the 
slight  interval  as  a rule  being  occupied  by  black  shale.  It  ranges 
from  1^  to  nearly  4 feet  in  thickness.  The  best  exposures  in  the  quad- 
rangle occur  along  Stony  Creek  (PI.  IV,  A,  p.  24)  and  the  Baltimore 
and  Ohio  Railroad  between  Moxhom  and  the  mine  of  the  Valley  Coal 
and  Stone  Company.  This  limestone  has  never  been  used  in  any  way. 

JOHNSTOWN  LIMESTONE  MEMBER. 

The  limestone  occurring  below  the  Upper  Kittanning  or  Cement 
coal  is  known  locally  as  the  Johnstown  cement  bed.  It  is  best 
developed  along  Stony  Creek  and  may  be  seen  to  advantage  on  the 
Baltimore  and  Ohio  Railroad  north  of  Kring,  where  it  is  6 feet 
thick  and  is  separated  from  the  coal  by  8 to  12  inches  of  shale.  Along 
the  spur  track  leading  from  the  north  end  of  the  Baltimore  and  Ohio 
tunnel  to  the  mine  of  the  Valley  Coal  and  Stone  Company  it  is  also 
conspicuous  but  slightly  thinner.  (See  PI.  VII,  A,  p.  48.)  The  sec- 
tions measured  by  hand  level  (see  pp.  44  and  47)  indicate  the  relations 
of  this  limestone  and  show  its  thickness  where  measured  in  this  part 
of  the  quadrangle.  The  bed  is  nearly  8|  feet  thick  near  Conemaugh 
depot  and  nearly  5 feet  in  the  section  along  the  Pennsylvania  Rail- 
road to  the  west,  approaching  Johnstown  depot.  To  the  east,  on 
Conemaugh  River,  it  is  exposed  just  at  the  northwest  apex  of  the 
first  big  meander.  It  must  be  thick  in  all  the  intermediate  territory. 
Its  outcrop  along  Stony  Creek  near  the  Rolling  Mill  mine  of  the  Cam- 
bria Steel  Company  is  also  conspicuous.  Northwest  of  Johnstown, 
near  the  old  Cambria  furnace  and  at  the  east  base  of  Laurel  Hill,  it 
outcrops  and  shows  just  above  the  waters  of  Laurel  Run.  Here  it  is 
a bluish  limestone  with  a few  streaks  of  calcite.  It  is  present  but 
not  very  thick  near  South  Fork,  and  is  also  reported  near  Scalp  Level, 
just  across  the  Somerset  County  border. 

In  the  reports  of  the  Second  Geological  Survey  of  Pennsylvania® 
this  bed  is  called  the  11  Ferriferous  limestone/ 1 but  its  identity  with 
the  limestone  of  the  same  name  of  the  Allegheny  Valley  was  left 
open  for  more  complete  and  harmonious  evidence  than  was  available 
when  the  report  on  Cambria  and  Somerset  counties  was  written. 


a Rept.  112, 1877,  pp.  150  et  seq. 


128  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

The  limestone  at  this  horizon  was  worked  at  one  time.  In  the 
report  of  the  Second  Geological  Survey,  Platt  mentions  the  Haws 
Cement  Works  as  utilizing  this  rock  occurring  on  Stony  Creek  not 
far  from  the  Rolling  Mill  mine.  He  describes  it  as  being  bluish  gray 
in  color,  hard,  and  brittle,  showing  small  crystals  of  iron  pyrites,  and 
containing  considerable  clay.  The  deposit  worked  was  dolomitic 
in  character.  The  sample  collected  near  Kring  for  analysis  is  also 
dolomitic  in  character.  (See  analysis  1.)  Such  high  magnesian 
limestones  have  been  used  in  the  manufacture  of  natural  cements 
near  Utica,  La  Salle  County,  111.,  in  the  Louisville  district  of  Indiana 
and  Kentucky,  and  in  the  Rosendale  district,  Ulster  County,  N.  Y. 
The  magnesia,  in  natural  cements  at  least,  may  be  regarded  as  equiva- 
lent to  lime  so  far  as  the  hydraulic  properties  of  the  product  are 
concerned.  The  presence  of  magnesium  carbonate  in  a natural 
cement  rock  is  merely  incidental,  while  the  silica,  alumina,  and  iron 
oxide  are  essential.  For  comparison  average  analyses  of  limestones 
from  the  different  districts  mentioned  above  are  given  below, 
together  with  that  of  the  limestone  near  Johnstown: 


Analyses  of  limestones  suitable  for  making  cement. 


! > 

2. 

3. 

4. 

Silica  (Si02) 

14.  44 

| 20. 92 

/ 13.34 

18. 04 

Alumina  (AI2O3) 

7.82 

\ 3.  46 

6. 18 

Ferric  oxide  (Fe203) 

1.54 

2.  35 

1.90 

2.63 

Manganese  oxide  (MnO) 

.20 

Lime  (CaO) 

25.  05 

26.  32 

31.  49 

25.23 

Magnesia  (MgO) 

13.  29 

12.  10 

11. 19 

12.  47 

Sulphuric  anhydride  (SO3) 

. 15 

a 1.81 

b.  78 

*n  t fNaoO 

.28 

| c.  18 
| 36.  73 

r n.  d. 

AlkaliesjK2Q 

. 86 

\ n.  d. 

Water  at  100°  C 

.28 

e 37, 07 

j d\.  20 

\ *33.31 

Ignition  loss  (includes  CO2) 

36.  48 

a Average  of  two  analyses.  d Result  of  one  analysis. 

b Average  of  five  analyses.  « Includes  only  CO2. 

c Average  of  two  analyses,  one  of  which  is  too  low. 

1.  Sample  collected  on  Baltimore  and  Ohio  Railroad  north  of  Kring.  Analysis  made  at  structural- 
materials  testing  laboratory,  United  States  Geological  Survey,  St.  Louis,  Mo.  A.  J.  Phillips,  analyst. 

2.  Average  of  five  analyses  of  natural  cement  rocks,  Utica,  111.  Eckel,  E.  C.,  Bull.  U.  S.  Geol.  Survey 
No.  243,  1905,  p.  340. 

3.  Average  of  six  analyses  of  natural  cement  rocks,  Louisville  district,  Indiana-Kentucky.  Eckel,  E.  C., 
Bull.  U.  S.  Geol.  Survey  No.  243,  1905,  p.  341. 

4.  Average  of  six  analyses  of  natural  cement  rocks,  Rosendale  district,  New  York.  Eckel,  E.  C.,  Bull. 
U.  S.  Geol.  Survey  No.  243,  1905,  p.  346. 

The  close  agreement  among  the  foregoing  analyses  strongly  suggests 
that  the  Johnstown  limestone  member  may  be  of  value  in  the  future 
for  local  use  only  in  making  natural  cement.  Its  cementation 
index  is  1.14,  which  places  it  in  class  A,  according  to  the  scheme  of 
E.  C.  Eckel.0  According  to  Eckel,  products  having  an  index  between 
1.00  and  1.15,  when  burned  at  sufficiently  high  temperature,  are 
slow  setting  and  high  in  tensile  strength.  They  include  the  “natural 
Portlands  ” and  allied  products.  If  not  burned  high  enough,  cements 


a Cements,  limes,  and  plasters,  1905,  pp.  198-199. 


BUILDING  STONE,  PAVING  BLOCKS,  ETC. 


129 


of  such  low  index  will  contain  free  lime  and  magnesia.  This  par- 
ticular product  near  Johnstown  stands  near  class  B (in  which  the 
cementation  indexes  run  from  1.15  to  1.60).  In  this  class  are  included 
most  American  natural  cements  and  nearly  all  European  Roman 
cements.  As  a rule  it  is  not  necessary  to  burn  these  products  at  so 
high  a temperature  as  those  in  class  A. 

The  composition  of  the  Johnstown  limestone  member  differs  from 
place  to  place,  as  the  following  analysis  of  a sample  collected  from 
the  vicinity  of  Mineral  Point  shows.  This  sample  is  low  in  alumina, 
magnesia,  and  silica  and  high  in  lime  and  differs  from  the  material 
of  the  corresponding  bed  near  Johnstown: 


Analysis  of  cement  rock,  Mineral  Point. 

Sample  collected  by  Lawrence  Martin  near  Mineral  Point.  Analyzed  at  structural-materials  laboratory, 
United  States  Geological  Survey,  St.  Louis.  A.  J.  Phillips,  analyst.] 


Silica  (Si02) 

Alumina  (A1203) 

Ferric  oxide  (Fe203) 

Manganese  oxide  (MnO)... 

Lime  (CaO) 

Magnesia  (MgO) 

Sulphuric  anhydride  (S03) 

Aikaiies{^° 

Water  at  100°  C 

Ignition  loss 


4.  97 
2.  57 
.56 
.48 

48.  36± 
1.  21  ± 
. 13 
.08 
.53 
. 09 
41.  17 


The  addition  of  clay  or  shale  of  proper  composition  would  be 
necessary  to  bring  rock  of  the  composition  shown  above  to  that  of 
a Portland  cement.  It  is  almost  certain  that  suitable  clay  or  shale 
exists  in  the  locality.  The  comparative  thinness  of  the  bed  will 
militate  against  its  extensive  use.  After  it  has  been  worked  some 
time  along  its  outcrop  it  will  have  to  be  mined  underground.  The 
expense  attached  to  such  operations  would  prevent  competition 
except  for  purely  local  purposes. 


BUILDING  STONE,  PAVING  BLOCKS,  AND  CONCRETE  MATERIALS. 


The  only  rock  suitable  for  building  stone  in  the  Johnstown  quad- 
rangle is  sandstone,  and  of  this  rock  there  is  a great  abundance. 
Locally  it  has  proved  of  great  value  in  the  construction  of  culverts, 
bridges,  etc.,  along  the  Pennsylvania  Railroad  and  in  the  construc- 
tion of  dwellings;  but  as  a rule  it  will  not  bear  the  cost  of  very 
distant  transportation.  The  gate  at  the  entrance  to  Grandview 
Cemetery,  Johnstown,  is  an  example  of  the  application  of  this  local 
rock  for  construction  purposes. 

The  sandstones  of  the  Conemaugh  have  been  used  in  certain  parts 
of  the  quadrangle  in  the  construction  of  dwellings.  In  the  north- 
695160— Bull.  447—11 9 


130  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

eastern  part  the  Morgantown  (“Ebensburg”)  sandstone  member 
has  been  so  used  with  very  satisfactory  results.  In  the  hills  about 
Johnstown  the  Mahoning  sandstone  member  is  exceedingly  massive 
in  places  and  is  capable  of  furnishing  dimension  stone  of  sizes  suit- 
able for  the  foundations  of  houses  and  for  culverts,  bridges,  chimneys, 
etc.  A great  deal  of  this  sandstone  has  been  quarried  from  the  out- 
crops of  the  Mahoning  sandstone  member,  especially  in  the  hills  east 
of  the  city,  and  used  for  the  purposes  enumerated. 

The  Pottsville  formation  is  made  up  almost  entirely  of  sand- 
stone. It  has  been  quarried  along  the  main  line  of  the  Pennsylvania 
Railroad  and  used  for  construction  purposes  and  in  the  manufacture 
of  concrete.  The  Conemaugh  Stone  Company  formerly  quarried  it 
for  use  in  construction  along  the  Pennsylvania  Railroad  from  a 
quarry  on  the  south  side  of  Conemaugh  River,  a few  miles  southeast 
of  Conemaugh  Furnace.  The  Pottsville  formation  outcrops  along  the 
Pennsylvania  Railroad  also  near  South  Fork,  Mineral  Point,  and  east 
of  Johnstown,  also  on  the  Baltimore  and  Ohio  Railroad  near  Paint 
Creek  and  farther  south.  The  sandstone  is  in  most  of  these  locali- 
ties a pure  coarse-grained  or  gritty  rock,  usually  weathering  to  a 
gray  or  gray-white  rock  of  pleasing  appearance.  It  seasons  rapidly 
and  firmly  and  withstands  the  eroding  action  of  the  elements  in  a 
manner  to  make  it  of  great  value  as  a building  stone. 

West  of  Coopersdale  the  sandstones  of  the  Pottsville  formation  are 
quarried  and  crushed  for  use  in  concrete.  The  quarry  is  owned  by 
A.  B.  Cooper,  who  also  controls  a quarry  on  the  Loyalhanna  lime- 
stone member  in  the  lower  part  of  the  hill.  The  limestone  is  crushed 
for  use  in  concrete  and  is  also  used  for  paving  blocks.  The  quarry 
on  the  sandstone  is  located  a few  hundred  feet  above  the  tracks  of  the 
Pennsylvania  Railroad  on  the  north  side  of  the  river.  The  sandstone 
is  very  pure  and  is  decidedly  coarse  grained  to  gritty  in  texture.  It  is 
blasted  out  without  much  regard  to  the  size  or  shape  of  the  product, 
the  only  requirement  being  that  the  fragments  be  as  small  as  pos- 
sible. The  larger  pieces  are  broken  up  and  the  stone  is  removed  to 
the  mill  on  the  railroad  by  means  of  small  cars  moving  on  an  inclined 
plane  and  controlled  by  a stationary  engine  at  its  foot.  At  the  mill  the 
sandstone  is  crushed  by  two  crushers  having  a capacity  of  100  and  300 
tons  a day  of  ten  hours.  It  is  then  conveyed  to  a wet  pan,  in  which 
it  is  further  reduced  in  size  and  thence  passed  through  screens  of  the 
proper  size,  from  which  it  is  conveyed  by  a bucket  conveyor  directly 
to  the  cars. 

Another  rock  used  in  the  manufacture  of  concrete  is  the  Loyalhanna 
limestone  member,  which  (see  p.  29)  occurs  at  the  top  of  the  Pocono 
formation.  It  is  about  45  feet  thick  in  the  Johnstown  quadrangle. 
It  is  not  a true  limestone  but  rather  a sandy  limestone.  It  weathers 


GLASS  SAND.  131 

in  a peculiar  and  characteristic  way,  well  shown  in  Plate  VI,  A, 
page  28.  This  siliceous  limestone  is  quarried  and  split  into  paving 
blocks  which  give  satisfaction,  and  is  crushed  for  use  as  ballast  in  rail- 
road beds.  For  both  uses  it  is  well  adapted,  as  its  calcareous  portion 
on  solution  and  recrystallization  tends  to  bind  the  fragments  solidly 
together  and  yet  leaves  sufficient  space  between  them  to  allow  the 
free  circulation  of  water.  The  siliceous  limestone  exposed  near  the 
viaduct  between  Mineral  Point  and  South  Fork  has  also  been  quarried 
for  paving  blocks. 

GLASS  SAND. 

The  question  has  been  raised  whether  the  pure  sandstone  occurring 
in  the  Pottsville  formation  in  the  Johnstown  quadrangle  might  not  be 
used  in  the  manufacture  of  glass,  especially  bottle  glass.  Sand  or 
crushed  sandstone,  as  is  well  known,  is  the  major  constituent  of  glass, 
forming  from  52  to  65  per  cent  of  the  mass  of  the  original  mixture,  or 
from  60  to  75  per  cent  of  the  .finished  product.  To  the  sand  is  due  the 
absence  of  color  (according  to  its  purity),  the  transparency,  brilliancy, 
and  hardness  of  glass.  For  the  finest  flint  ware,  such  as  optical  and 
cut  glass,  only  the  purest  sand  can  be  employed.  For  plate  and  win- 
dow glass,  which  are  commonly  pale  green,  absolute  purity  is  not 
essential,  but  generally  the  sand  should  not  carry  more  than  0.2  per 
cent  of  iron  oxide.  Green  and  amber  glass  for  bottles,  jars,  and  rough 
structural  work  can  be  made  from  sand  relatively  high  in  impurities, 
but  an  excess  of  iron  is  to  be  avoided  by  careful  selection.  Washing 
may  be  necessary  to  remove  the  iron,  and  magnetic  separation  may 
have  to  be  employed.  Clay  in  the  raw  material  is  objectionable,  as 
it  clouds  the  glass,  but  it  may  be  removed  in  part  by  washing.  Mag- 
nesia is  troublesome  because  it  makes  the  batch  difficult  to  fuse.  If  a 
sandstone  is  used  as  a source  of  glass  sand,  it  should  be  friable,  so  as 
to  be  readily  crushed. 

The  sandstone  derived  from  the  Pottsville  formation  is  in  its  original 
form  a massive  rock,  in  some  places  friable  but  in  others  not;  the  less 
friable  portions  are,  however,  readily  crushed.  In  many  parts  of  the 
quadrangle  the  sandstone  of  the  Pottsville  fills  all  the  requirements 
of  a glass  sand  for  the  manufacture  of  bottles,  jars,  and  rough  struc- 
tural material;  where  the  amount  of  oxide  of  iron  is  excessive  it  may 
be  corrected  by  the  addition  of  small  amounts  of  manganese  dioxide 
or  other  decolorizing  agents.  The  following  analysis  of  a sample  of 
friable  sandstone  from  the  Pottsville  formation,  collected  on  the  west 
flank  of  Laurel  Ridge,  not  far  from  Seward,  shows  the  character  of  this 
sandstone  at  this  point,  and  it  is  quite  probable  that  sandstone  of 
equally  great  purity  may  be  collected  at  other  points  where  the  Potts- 
ville outcrops  in  this  area : 


132  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 
Analysis  of  glass  sand  from  Pottsville  formation  on  westflanh  of  Laurel  Ridge,  near  Seward. 


[Made  by  A.  J.  Phillips  at  the  structural-materials  testing  laboratory  of  the  United  States  Geological 

Survey  at  St.  Louis,  Mo.] 


Silica  (Si02) 97.  54 

Alumina  (A1203) 81 

Ferric  oxide  (Fe203).. .09 

Lime  (CaO) • i.  04 

Magnesia  (MgO) .06 

Alkalies  ^ 

Water  at  100°  C 03 

Ignition  loss 49 


100.  24 

The  amount  of  impurities  is  notably  small.  Iron  oxide  falls  well 
within  the  outside  limits  demanded  for  bottles,  jars,  and  rough  struc- 
tural material.  The  amount  of  clayey  material  is  very  small,  as  is 
also  the  magnesia. 

The  sandstone  of  the  Pottsville  should  offer  no  serious  obstacle 
to  being  ground  to  the  requisite  fineness  (say  to  pass  through  a 20  to 
50  mesh  sieve).  In  prospecting  for  glass  sand  only  the  clearest  and 
whitest  sand  should  be  selected,  and  before  exploitation  complete 
quantitative  analyses  and  furnace  tests  of  representative  samples 
should  be  made. 

IRON  ORES. 


HISTORY. 

But  one  bed  of  iron  ore  in  the  Johnstown  quadrangle  deserves 
mention,  and  that  one  is  now  of  historic  interest  only.  The  interest 
attached  to  the  ore  is,  however,  great,  for  its  presence  in  the  hills  near 
Johnstown  was  perhaps  the  main  factor  in  determining  the  location 
of  the  present  great  plant  of  the  Cambria  Steel  Company,  which 
sought  this  position  for  its  works  owing  to  the  close  association 
between  the  ore  and  the  underlying  coal  beds.  With  the  appearance 
of  the  cheap  Lake  ores  on  the  market  the  Johnstown  iron  ore  ceased 
to  be  of  importance.  At  present  it  is  not  worked,  and  very  little  first- 
hand information  is  to  be  obtained  regarding  it.  The  following  notes 
are  simply  a compilation  from  the  report  of  the  Second  Geological 
Survey  of  Pennsylvania®  and  are  given  here  to  make  this  report  of 
the  mineral  resources  of  the  Johnstown  quadrangle  complete 


JOHNSTOWN  ORE  BED. 

EXTENT. 

The  Johnstown  ore  bed  is  found  in  the  center  of  the  Johnstown 
Basin.  Its  eastern  outcrop  appears  a short  distance  west  of  Cone- 
maugh  depot,  where  it  occupies  a position  well  up  on  the  hillsides 


a Rept.  H2,  1875,  pp.  Ill,  112, 118  et  seq. 


IRON  ORES. 


133 


above  the  railroad.  Thence  it  descends  slowly  westward,  approaching 
water  level  at  Hinckston  Run,  and  after  crossing  the  svnclinical  axis 
it  again  rises  toward  the  Laurel  Ridge  anticline  and  comes  to  the 
surface  on  the  eastern  flank  of  Laurel  Ridge.  In  the  hills  along  the 
south  bank  of  the  Conemaugh  it  has  never  been  found,  although 
repeated  search  has  been  made  for  it.  Its  horizon  has  been  deter- 
mined may  times  and  the  vertical  distance  between  it  and  the  upper 
Freeport  (Coke  Yard)  coal  has  been  accurately  measured.  At 
Johnstown  this  interval  is  about  50  feet.  This  same  iron-ore  bed  is 
known  to  exist  on  Mill  Creek  southeast  of  Johnstown,  where  it  was 
benched  for  many  years  prior  to  1875  by  Dr.  Schoenberger,  the  ore 
furnishing  the  material  on  which  two  small  furnaces  were  run.  The 
same  ore  was  mined  near  and  smelted  at  the  old  Cambria  furnace, 
near  the  base  of  Laurel  Hill. 

CHARACTER  OF  THE  ORE. 

The  ore  bed  at  the  opening  of  the  Cambria  Company’s  mine  on  the 
west  bank  of  Hinckston  Run  was  divided  into  two  bands  by  a stratum 
of  fire  clay  or  shale  which  ranged  from  an  inch  to  a foot  in  thickness 
and  which  crumbled  when  exposed  to  the  weather,  losing  its  water 
slowly  and  changing  in  color.  The  upper  bench  was  much  richer  in 
iron  than  the  lower,  the  latter  being  calcareous;  but  the  ore  from  both 
benches  contained  sufficient  lime  to  flux  and  was  charged  into  the 
furnace  with  the  coke  without  limestone.  The  ore  yielded  about  30 
per  cent  of  metallic  iron  when  carefully  treated  in  the  furnace,  but 
sometimes  ran  below  this  figure  and  occasionally  rose  above  it.  Its 
character  is  expressed  by  the  following  analyses,  furnished  by  T.  T. 
Morrell : 

Analysis  of  iron  ore  from  Johnstoun  bed. 


Silica 4.885 

Alumina 1.  552 

Carbonate  of  iron 52.  330 

Sesquioxide  of  iron 15.230 

Carbonate  of  lime 15.  285 

Carbonate  of  magnesia 9.390 

Phosphoric  acid 530 

Sulphur 850 

Water. 

Metallic  iron,  35.  930. 


Mr.  Morrell  reports  finding  also  a strong  trace  of  manganese.  The 
ore  was  calcined  before  being  used  in  the  furnace;  the  calcination  was 
carried  out  in  large  open  heaps  near  the  mine,  at  an  expense  of  about 
10  per  cent  of  fuel.  The  following  analyses  by  Mr.  Morrell  show  the 
general  character  of  the  ore  after  calcining,  from  both  the  upper  and 
lower  benches : 


134  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 


Analysis  of  calcined  iron  ore  from  Johnstown  bed. 


Upper 

bench. 

Lower 

bench. 

Peroxide  of  iron 

77.64 

45. 86 

Silica 

7.34 

21.94 

Alumina 

1.02 

4.02 

Sesquioxide  of  manganese 

1.39 

.86 

Lime 

10. 10 

19.  94 

Magnesia 

1.01 

6. 35 

Phosphoric  acid 

.99 

.53 

Sulphuric  acid 

.52 

.33 

100. 01 

99.85 

Metallic  iron 

54. 350 

32. 110 

Phosphorus 

.424 

.232 

Sulphur 

.210 

.133 

PHYSICAL  FEATURES  OF  THE  ORE  BED. 

The  ore  bed  is  invariably  underlain  by  shale  and  the  roof  is  chiefly 
of  the  same  material,  being  locally  replaced  by  massive  sandstone 
containing  lumps  of  carbonate  ore.  The  roof  shale  shows  a decided 
tendency  to  crumble,  and  after  the  ore  has  been  removed  it  sinks 
steadily,  gradually  reducing  the  height  of  the  gangways.  This 
behavior  of  the  roof  has  been  a source  of  constant  annoyance,  and  has 
required  the  closest  watching  to  avoid  accidents.  To  counteract  the 
sinking,  “ shanties”  4 feet  high,  consisting  of  strong  timbers  laid 
crosswise,  are  constructed  at  short  intervals.  In  places  these  power- 
ful logs  are  crushed  so  tightly  together  as  not  to  exceed  2 feet  in 
height.  The  irregularities  of  the  bed  are  perhaps  one  of  its  most 
striking  features.  These  irregularities  consist  of  11  rolls7’  and  “ horse- 
backs,” which,  though  numerous,  do  not  interfere  with  the  general 
plan  of  working  the  ore.  The  system  employed  in  mining  is  known 
as  the  long-wall  method,  the  best  and  most  economical  of  all  systems 
wherever  practicable.  (See  pp.  105-112.)  By  this  method  the  ore  is 
taken  from  along  a line  of  wall  which  as  it  advances  includes  within 
a certain  distance  all  the  ore  under  the  hill  as  far  as  the  point  reached. 

The  ore  oxidizes  rapidly  at  the  outcrop,  changing  from  a dove  color 
to  a rich  brown,  the  former  being  the  color  of  the  unaltered  carbonate, 
the  latter  of  the  hydrous  oxide,  or  limonite,  resulting  from  the  oxida- 
tion of  the  carbonate.  The  average  thickness  of  the  ore  at  the 
Hinckston  Run  mine  is  about  2 feet;  it  changes,  however,  in  thick- 
ness abruptly,  the  upper  band  thickening  and  the  lower  thinning,  and 
vice  versa.  The  following  measurements  made  at  different  points  in 
the  mine  serve  to  show  the  varying  thickness  of  the  ore  bands.  The 
third  section  was  measured  at  a distance  of  10  feet  from  the  place 
where  the  second  measurement  was  made,  and  the  fourth  1.5  feet  still 
farther  southwest. 


WATER  RESOURCES. 


135 


Sections  of  Johnstown  ore  bed. 


Ft.  in. 

I (1)  Sandstone  with  bowlders  of  ore. 


Ore 5 

Indurated  fire  clay 5 

Ore 71 

Shale. 

(2)  Shale  roof. 

Ore,  parted  by  1 inch  of  fire 
clay 2 4 


Ft.  in. 

(3)  Shale  roof. 

Ore 1 2 

Shale  floor. 

(4)  Shale  roof. 

Ore 1 

Parting 4 

Ore 1 

Shale  floor. 


WATER  RESOURCES. 

The  Johnstown  quadrangle  is  a well-watered  region.  Most  of  the 
towns  derive  their  water  from  the  headwaters  of  the  smaller  creeks 
flowing  into  the  main  drainage  channels — Stony  Creek,  Conemaugh 
and  Little  Conemaugh  rivers,  and  Blacklick  Creek  with  its  North  and 
South  branches.  These  streams  are  fed  by  multitudes  of  springs  as 
well  as  by  the  ordinary  rainfall.  This  water  is  stored  in  reservoirs  to 
insure  a constant  and  adequate  supply.  The  water  is  excellent, 
because  the  slopes  from  which  most  of  it  comes,  though  of  small 
extent,  are  in  general  well  wooded  and  comparatively  free  from  habi- 
tation. The  city  of  Johnstown  obtains  its  water  chiefly  from  three 
storage  reservoirs,  two  on  Mill  Creek  and  one  on  Dalton  Run.  South 
Fork  obtains  its  supply  from  a storage  reservoir  on  Sandy  Run.  The 
town  of  Wehrum  procures  water  from  a reservoir  on  Rummel  Run, 
and  it  is  understood  that  the  town  of  Vintondale  also  has  a reservoir 
on  a stream  to  the  southeast.  The  town  of  Windber  and  associated 
mining  villages,  lying  in  part  within  the  Johnstown  quadrangle,  are 
supplied  partly  from  a storage  reservoir  on  Little  Paint  Creek.  For 
industrial  purposes  the  Cambria  Steel  Company"  has  constructed  a 
large  reservoir  on  Hinckston  Run.  During  most  of  the  y"ear  the  flow 
of  the  streams  is  fairly  adequate,  but  during  the  dry  season  of  the 
autumn  the  supply"  is  likely  to  run  low.  During  the  summer  of  1906 
the  streams  all  maintained  a good  flow  of  water. 

Away  from  the  railroads  the  inhabitants  of  the  region  depend 
mostly  on  wells.  Many  of  these  wells  have  been  driven  as  far  down 
as  coal  beds,  which  are  almost  universally"  in  water-bearing  zones. 
The  water  obtained  from  such  beds  is  commonly  sulphurous  and 
generally  considered  very  wholesome.  Springs  are  very  abundant 
but  do  not  appear  to  be  large.  The  springs  generally  issue  from  coal 
beds  or  just  above  impervious  clay  beds.  Though  the  volume  in 
most  such  springs  is  not  large,  in  purity"  the  water  can  not  be  excelled. 
Many  of  the  drill  holes  put  down  in  this  area  have  tapped  water- 
bearing beds,  but  almost  all  the  drillings  have  been  made  in  search 


136  MINERAL  RESOURCES  OF  JOHNSTOWN,  PA.,  AND  VICINITY. 

of  coal  beds,  and  little  or  no  attention  has  been  paid  to  the  water- 
bearing strata.  These  usually  have  been  either  sandstone  beds  or 
coal  beds.  Such  a hole  was  drilled  near  the  confluence  of  North  Fork 
and  South  Fork  of  Bens  Creek  in  Somerset  County,  near  Mishler. 
The  locality  is  known  as  Sulphur  Springs.  The  water  probably 
issues  from  the  Upper  Kittanning  coal  bed,  as  the  drill  hole  is 
understood  to  be  very  shallow. 


INDEX. 


A. 


Page. 


C. 


Page. 


Allegheny  formation,  character  and  distribu- 


tion of 22-27,44 

clays  in 114 

brick  from 114 

coals  in. . . 22-27, 44-61, 64-78, 80-91 , 92-95, 96-101 
See  also  'particular  coals. 

limestones  in 126-129 

sections  of 22-23, 27, 92 

figure  showing 24 

shales  in 115 

Alluvium,  occurrence  and  character  of 15 

Ashley,  G.  H.,  work  of 9 


B. 

Baltimore  and  Ohio  Railroad,  bench  marks 


along 14 

Barnesboro  syncline,  description  of 24 

B coal.  See  Lower  Kittanning  coal. 

Bear  Rock  Run,  coal  at,  analysis  of 70 

Beaverdale,  coal  at,  section  of,  figure  showing.  66 

Beaverdam  Run,  coal  at,  section  of,  figure 

showing 66 

Bench  marks,  location  of 14 

Bennington,  coal  at 69 

coal  at,  analysis  of 70 

coking  of 39 

Bens  Creek,  coal  on 49, 54 

coal  on,  analysis  of 70 

section  of,  figure  showing 55 

Bens  Creek  (South  Fork),  coal  on 43 

Beulah  Road,  bench  mark  on 14 

Big  Bend,  coal  at 79, 81 

section  at 90 

Blacklick  Creek,  coal  on 22,80-81 

rocks  on 20 

section  on,  figure  showing 24 

Blacklick  Creek  district,  clays  of. . . 113-114, 124-125 

coals  of 80-95 

position  of 79-80 

extent  of 78-79 

Blacklick  Creek  seam.  See  Lower  Kittan- 
ning coal. 

Bolivar  clay  member,  character  and  distribu- 
tion of 25 

Brick  industry,  firms  engaged  in 156 

Briquetting  tests,  results  of 87-88, 99-100 

Brookvillecoal,  character  and  distribution  of.  23, 

27,41-42,60-61,77-78 

sections  of 60,91,92 

figures  showing 24, 78 

See  also  Dirty  A coal. 

Buffalo  sandstone  member,  character  and  dis- 
tribution of 20 

section  of 17 

Butler  sandstone  member,  character  and  dis- 
tribution of 25 


Cambria,  coal  at  and  near 54, 55 

coal  at  and  near,  section  of,  figure  show- 
ing  55 

Carboniferous  system,  occurrence  and  char- 
acter of 16-29 

Catskill  formation,  character  and  distribu- 
tion of 29 

section  of 30 

C coal,  position  of 80 

See  also  Middle  Kittanning. 

C'  coal.  See  Upper  Kittanning  coal. 

Cement.  See  Portland  cement. 

Cement  coal.  See  Upper  Kittanning  coal. 

Cement  rock,  natural,  analyses  of 128, 129 

Chickaree,  triangulation  station  at 11-12 

Clapboard  Run,  clay  on 117 

coal  on 49, 53, 58, 59, 60 

sections  of 60 

figures  showing 50, 55, 59 

section  of,  figure  showing 24 

structure  near 34 

Clarion  coal,  character  and  distribution  of.  23, 27, 61 

section  of 90,91,92 

'figures  showing 24,61 

Clay,  character  and  distribution  of 113-126 

See  also  Flint  clays;  Plastic  clays. 

Clay  industry,  firms  engaged  in 125-126 

Coal,  mining  of,  bibliography  of 113 

mining  of,  description  of 102-112 

figures  showing 103, 106, 107, 108 

occurrence  and  character  of 35-101 

Coal  deposits,  description  of,  by  districts. . . 42-101 
Coke  Yard  coal.  Sec  Upper  Freeport  coal. 

Coking  tests,  results  of 72-73, 85, 98-99 

Conemaugh  formation,  character  and  distri- 
bution of \ 16-22,43 

clays  in 113,114 

coals  in 19,20-22,43-44,62-64 

limestone  in 126 

members  of,  description  of ...  18-22 

sandstones  of 129-130 

view  of 20 

sections  of :...  16-18, 21-22, 115-116 

shales  in 115 

Conemaugh  Furnace,  coal  from 101 

coal  from , analyses  of 41-42 

Conemaugh  Furnace  district,  clays  of 114 

coals  of 96-102 

extent  of 96 

Conemaugh  River,  clays  on 121 

coals  on 49, 51, 53, 56, 57-58, 65, 67, 69, 96, 97 

commerce  by 9-10 

description  of 9, 11 

limestone  on 127 

rocks  on 15,28,29 

sections  of 30 

figure  showing 101 


137 


138 


INDEX. 


Page. 

Conemaugh  slope,  coal  from 49 

coal  from,  analysis  of 42 

section  of,  figures  showing 50, 59 

Conglomerate  rock.  See  Pottsville  formation. 
Connoquenessing  sandstone  member,  charac- 
ter and  distribution  of 27-28 

Contours,  structure,  explanation  of 30-31 

Conveyor  method,  description  of 105-112 

Conveyors,  description  of 109-110 

Coopersdale , clay  at 118 

coals  at  and  near 27, 48, 51, 57, 60 

section  of,  figure  showing 59 

sandstones  near. . 130 

section  at 23 

figure  showing 24 

Cramer,  coal  near,  section  of 96 

Cupola  tests,  results  of 73-75 


Dale,  coal  at 52,54,56 

coal  at,  analysis  of 40, 42 

sections  of,  figures  showing 50, 52, 55 

Dalton  Run,  clay  on 117 

coal  on 25, 54 

section  of 26 

sections  of,  figure  showing 55 

D coal.  See  I.ower  Freeport  coal. 

Devonian  system,  occurrence  and  charaeterof.  29-30 

Dilltown,  clay  near 124 

clay  near,  analysis  of 124 

coal  near 79,83 

section  of,  figure  showing 89 

D’Invilliers,  E.  V.,  on  coals 80,82-83,92 

on  structure 82 

Dirty  A coal,  analysis  of 41 

character  and  distribution  of 39-40 

See  also  Brookville  coal. 

Drainage,  description  of 9-10 

relation  of,  to  structure. 10 

Drainage,  mine,  methods  of 104 

Dunlo,  coal  at,  section  at,  figure  showing 66 


E. 

East  Conemaugh,  coal  near,  section  of,  figure 


showing 50 

section  near 47 

Ebensburg,  triangulation  station  at 12 

Ebensburg  quadrangle,  coal  of 68 

coal  of,  analyses  of 67,70 

Ebensburg  sandstone.  See  Morgantown  sand- 
stone member. 

E coal.  See  Upper  Freeport  coal. 

Economic  geology,  account  of 35-136 

map  showing Pocket. 

Ehrenfeld,  coal  at  and  near 37, 65, 66, 73 

coal  at  and  near,  analysis  of 41-42, 76 

coking  of 38,72,74 

cupola  tests  of 73-75 

section  of,  figure  showing 66 

producer-gas  tests  of 76 

limestone  near 126-127 

rocks  at  and  near 20, 21, 25 

sections  at 21-22, 65 

figure  showing 77 

shale  near 123 


Page. 

Elevations,  location  and  height  of 10-11 

Elton,  coals  near 92 

rocks  near 19 

Expedit  post  office.  See  Twin  Rocks. 

F. 

Falls  Run,  coal  at 58 

Ferndale,  coal  near 52 

“ Ferriferous  limestone,”  correlation  of 127 

Flint  clays,  analyses  of 121, 122, 124 

character  and  distribution  of 113- 

117, 121-123, 124, 125 

sections  of 115-116, 122, 125 

Four-foot  coal.  See  Upper  Freeport  coal. 

Foustwell,  coal  near 59, 60 

section  near 27 

Franklin,  coal  at  and  near 51, 53, 58, 59, 60 

coal  from,  analysis  of 40, 42 

coking  of 39 

sections  of,  figures  showing 55,59 

structure  near 34 

Frankstown,  coal  near 53, 60 

coal  near,  section  of,  figures  showing 50, 57 

Fulton,  John,  work  of 43 

Fye  place,  triangulation  station  on 13 

G. 

Gallitzin,  coal  near 65 

coal  near,  section  of,  figure  showing 66 

Gallitzin  coal,  character  and  distribution  of. . 20, 

43,64 

Geography,  outline  of 9-10 

Glass  sand,  analysis  of 132 

character  and  distribution  of 131-132 

Greenbrier  limestone,  character  and  distribu- 
tion of 29 

Grubtown , coal  at,  sections  of,  figure  showing.  50 

H. 

Harlem  coal,  character  and  distribution  of . . . 19 

Haulage,  methods  of 104-105 

Headings,  character  of 102 

Hinckston  Run,  coal  on 49 

coal  on,  section  of,  figure  showing 50 

iron  ore  on 133 

Homewood  sandstone  member,  character  and 

distribution  of 27-28 

I. 

Ingleside,  bench  mark  at 14 

coal  near 43,57 

sections  of,  figures  showing 59, 93 

Ireland,  W.  G.,  work  of 73 

Iron  ores,  history  of 132, 133 

location  of 18, 132 

See  also  Johnstown  ore. 

Island  Park,  coal  near 43 

coal  near,  section  of,  figure  showing 50 


J. 


Johnstown,  bench  marks  at  and  near 14 

clays  near - 116 

coals  in  and  near 25, 26, 35, 43, 58-59 

analyses  of 40,42 

sections  of 26 


INDEX, 


139 


Tagc. 

Johnstown,  coals  in  and  near,  sections  of,  fig- 


ures showing 50,55,59 

rocks  near 19,20,21,25 

sections  near 17-18, 22-23, 115-116 

shales  near 115 

water  supply  of 135 

See  also  Johnstown  district. 

Johnstown  Basin,  description  of 32,33 

Johnstown  district,  clays  of 113, 115-119 

coals  of 25,43-61 

analyses  of 40-42 

sections  of,  figures  showing 50, 52, 55 

description  of 42 

shales  of 115,119-121 

analyses  of 120,121 

brick  from 119 

Johnstown  limestone  member,  character  and 

distribution  of 26, 127-129 

clay  below 117 

analysis  of 117 

limestone  of 127-129 

analyses  of 128 

view  of 48 

Johnstown  ore  bed,  analyses  of 133,134 

character  and  distribution  of.  18, 21, 126, 132-135 

sections  of 135 

Johnstown  syncline,  description  of 32, 33 

K. 

Kernville , clay  at 118 

coals  in  and  near 53,56,57,58 

sections  of,  figures  showing 52,59 

section  near 46 

Kittanning  sandstone  member,  character  and 

distribution  of 27 

Kr ing , bench  mark  at 1 4 

clay  near 119 

coal  near 26, 28, 43, 54, 56, 58, 61 

section  of 61 

figure  showing 55 

limestone  near,  analysis  of 128 

rocks  near 15,26 


L. 

Laurel  Ridge, clays  on 115, 116, 125 

glass  sand  on,  analysis  of 132 

iron  ore  on 133 

location  and  occurrence  of 10 

rocks  on * 28,29 

Laurel  Ridge  anticline,  description  of 33-34 

Laurel  Run,  coal  on 57 

coal  on,  section  of,  figure  showing 59 

limestone  on 127 

Lemon  coal.  See  Upper  Freeport  coal. 

Limestone,  analyses  of 128,129 

character  and  distribution  of 123-129 

Limestone  coal.  Sec  Lower  Freeport  coal. 

Little  Conemaugh  River,  structure  on 34 

Llanfair,  coal  at C9 

coal  at,  analysis  of 70 

section  of 77 

Lloydell,  coal  from,  analyses  of 37, 70 

Long-wall  system,  description  of 105-112 

figures  showing 106, 107, 108 

recommendation  of 105 


Page. 

Lower  Allegheny  coals,  character  and  distri- 
bution of 39- 


40, 60-61, 77-78, 89-91, 95 
See  also  Brookville  coal;  Clarion  coal; 

Dirty  A coal. 

Lower  Freeport  coal,  character  and  distribu- 
tion of 25, 35, 51-52, 67, 80-82, 93, 96 


sections  of 22,44,46 

figures  showing 24, 52, 81 

view  of 24 

Lower  Freeport  limestone  member,  char- 
acter and  distribution  of 25, 127 

view  of 24 

Lower  Kittanning  clay  member,  character 

and  distribution  of 27 

Lower  Kittanning  coal,  analyses  of 36-37 

40-42,58,69-70,71,73,76, 


84, 85, 86, 87, 88, 95, 97, 99, 100 


briquetting  tests  of 87-88, 97, 99-100 

character  and  distribution  of. . . 27, 34, 36, 57-60, 
69, 76-77, 82-83, 88, 94-95, 97, 101 

clay  below 117-118,123,125 

analysis  of 118 

coke  from,  analyses  of 73,85,99 

coking  tests  of 38-39, 58, 72-73, 85, 98-99 

cupola  tests  of 73-75 

producer-gas  tests  of 76, 86 

sections  of 23, 47, 48, 77, 79, 101 

figures  showing 24, 59, 77, 89, 95, 101 

steaming  tests  of 70-72, 83-85, 97, 98 

structure  map  of Pocket. 

explanation  of 30 

washing  tests  of 86-87, 99 

“ Lower  Productive  Coal  Measures.”  See 
Allegheny  formation. 

Loyalhanna  limestone  member,  character 

and  distribution  of 29 

use  of,  foj  concrete 130-131 

view  of 28 


M. 

Mahoning  coal,  character  and  distribution  of. . 22, 

43,64 

section  of 44 

Mahoning  sandstone  member,  character  and 

distribution  of 20-22 

sections  of 18,21-22 

use  of,  for  building 130 

Map,  economic  and  structural,  of  Johnstown 

quadrangle Pocket. 

Map,  index,  showing  position  of  Johnstown 

quadrangle 9 

Mardis  Run,  clay  on 25, 114, 124 

coal  on 79, 80, 81, 82 

section  of,  figure  showing 81 

Martin,  Lawrence,  work  of 9 

Mauch  Chunk  shale,  character  and  distribu- 
tion of 28-29 

sections  of 28,29 

view  of 28 

Mercer  coal,  character  and  distribution  of 61 

section  of 61 

Mercer  shale  member,  character  and  distribu- 
tion of 27-28 

clays  of 114, 119, 121-122, 125 


140 


INDEX. 


Pago. 

Mercer  shale  member,  clays  of,  analyses  of.  121, 122 


clays  of,  section  of 119, 122, 125 

quarry  on,  view  of 28 

section  of 125 

shale  of 120-121,125 

analysis  of 121 

Middle  Kittanning  coal,  character  and  dis- 
tribution of 26, 44, 56-57, 82, 94, 96 

sections  of 79, 82, 96 

figure  showing 24 

Mill  Creek,  clay  on 117 

coal  on 51,53,54 

iron  ore  on 133 

section  on 45 

Miller  coal.  See  Lower  Kittanning  coal. 

Mineral  Point,  coal  near 67,77-78 

coal  near,  sections  of,  figures  showing 68, 77 

view  of 24 

limestones  at,  analyses  of 129 

rocks  near 15 

Mineral  Point  district.  See  South  Fork- 
Mineral  Point  district. 

Mineral  resources,  description  of 35-136 

Mining,  facility  of 10 

Mississippian  series,  occurrence  and  character 

of 28-29 

Morgantown  sandstone  member,  character 

and  distribution  of 19 

section  of 16 

Morrellville,  coal  near 54, 58 

Moxhom,  coal  near 54,56,93 

coal  near,  analysis  of 40, 42 

sections  of,  figures  showing 50,55 

limestone  near 127 

N. 

Nanty  Glo,  bench  mark  at 14 

coal  of 78-79,80,81-82,83 

analyses  of 40, 42 

coking  of 39 

sections  of,  figures  showing 81,89 

New  Germany,  coal  near 67 

P. 

Paint  Creek,  coal  near 60,94 

rocks  near 15,28,60-61 

sandstone  near 130 

section  near 28 

Peggy s Run,  coal  on 51, 53, 56, 58, 60 

section  on,  figure  showing 24 

Pennsylvania,  cooperation  with 9 

Pennsylvania  Railroad,  bench  marks  along. . 14 

Pennsylvanian  series,  occurrence  and  char- 
acter of 16-28 

Phalen,  W.  C.,  work  of 9 

Pillars,  details  of 103 

Plastic  clays,  analyses  of 117,118 

character  and  distribution  of 114-115, 

117-119,123,125 

sections  of 119 

Platt,  Franklin,  on  Summerhill  mine 62-64 

Pleasant  Hill,  clays  on 116 

Pleistocene  deposits,  occurrence  and  character 

of 15 


Page. 

Pocono  formation,  character  and  distribution 


of 29 

topography  of 10 

Portland  cement,  materials  for 26 

Pottsville  formation,  character  and  distribu- 
tion of 27-28 

coals  of 61,78 

sections  of 61,78 

See  also  Mercer  coal. 

glass  sand  from 131-132 

analysis  of 132 

sandstones  of 130 

section  of 28 

topography  of 10 

Producer-gas  tests,  results  of 76,86 

Prospect  Hill,  shale  on 120 

Prossers  Knob,  coal  in 43 

section  of 17-18 

Puritan,  coal  at,  analysis  of 68 

coal  at,  section  of,  figure  showing 66 

Q. 

Quaternary  system,  occurrence  and  character 

of 15 

R. 

Recent  deposits,  occurrence  and  character  of.  15 

Red  shale,  character  and  distribution  of 19, 20 

Relief,  description  of 10-11 

Rexis,  coal  near 80 

coal  near,  section  of,  figure  showing 81 

River  deposits,  occurrence  and  character  of. . 15 

Room  and  pillar  system,  description  of 102-105 

Rooms,  character  of 102-103 

Roxbury,  coal  at,  section  of,  figure  showing. . 50 

Rummel  Run,  coal  on,  section  of,  figure  show- 
ing  89 

S. 

St.  Clair  Run,  coal  on 49-50, 58 

coal  on,  section  of,  figure  showing 50, 59 

Salix,  bench  mark  at 14 

Salt  Lick  Run,  coal  on,  section  of,  figure  show- 
ing   68 

Saltsburg  sandstone  member,  character  and 

distribution  of 19-20 

Sams  Run,  coal  on 49, 52, 54, 56 

coal  on,  sections  of,  figures  showing. . . 50, 52, 55 
Sandstone,  character  and  distribution  of. . 129, 131 

use  of,  for  building 129 

Sandy  Ridge,  clay  from,  analysis  of 112 

Scalp  Level,  bench  mark  at 14 

coals  near 91,92 

analysis  of 41-42 

limestone  at 127 

section  at 92 

Seidel,  George,  work  of 13 

Seward,  bench  mark  at 14 

clays  at 114 

coal  at 96,97,101 

analysis  of 37 

coking  of 38,39 

section  of,  figure  showing 101 

glass  sand  near,  analysis  of 132 


INDEX. 


141 


Page. 

Shale,  analyses  of. 120, 121 

character  and  distribution  of  . 113, 

115,119-121,123 

Sherbine  farm,  triangulation  station  on 12-13 

Sheridan,  clay  near 114-115, 119 

coal  near 61 

quarry  near,  view  of 28 

rocks  near 15 

shale  near 115,120-121 

analysis  of 121 

Shingle  Run,  clay  on 116 

Six-foot  coal,  analysis  of 41 

character  and  distribution  of 39-40 

See  also  Brookville  coal. 

Solomons  Run,  coal  on 49, 52, 54, 56, 58 

coal  on,  analysis  of 40, 42 

section  of,  figures  showing 52, 55, 57 

South  Fork  (town),  clay  at 121-122, 123 

clay  at,  section  of 122 

coal  at  and  near 67, 76, 77-78 

production  of 69 

sections  of,  figures  showing 68, 77, 78 

limestone  near 126-127 

rocks  at  and  near 20, 25 

section  at,  figure  showing 24 

water  supply  of 135 

See  also  South  Fork-Mineral  Point  dis- 
trict. • 

South  Fork  (river)  coals  on 35,36,64,65,70,92 

coals  on,  analyses  of 40,41-42,70 

sections  of,  figure  showing 66 

dam  on,  view  of 20 

rocks  on 62 

South  Fork-Mineral  Point  district,  clays  of . . . 113, 

114, 121-123 

coals  of 25,62-78 

position  of 62 

extent  of 61 

shales  of 123 

Spirit  leveling,  progress  of 13-14 

Springs,  character  and  distribution  of 135 

Steaming  tests,  details  of 70-72,83-85,98 

Steaming  value,  comparative,  of  coals 37 

Stony  Creek,  bench  mark  on 14 

clays  on 114,116 

coal  on  and  near 49, 51, 53, 54, 55, 58, 61 

analyses  of 40, 42, 93, 94 

sections  of,  figure  showing 52 

views  of 24,48 

description  of 10 

limestone  near 127 

rocks  on 15, 20, 25, 26, 28 

sections  on 44, 46-47, 48 

figures  showing 50 

Stratigraphy,  description  of 14-30 

Structure,  representation  of 30-31 

Structure  in  Johnstown  quadrangle,  descrip- 
tion of 31-34 

map  showing 31,  Pocket 

relation  of,  to  drainage 10 

Summerhill,  coal  near 62-64 

coal  near,  analyses  of 63, 64 

section  of 63 

rocks  near 19 


Page. 

Summerhill  sandstone  member,  character  and 


distribution  of 18-19 

Surveys,  description  of 11-14 

T. 

Ten  Acre  Bridge,  coal  at 53 

coal  at,  section  of,  figure  showing 55 

Thomas,  J.  I.,  on  mining  at  Vintondale 108-112 

Tipples,  character  of 105 

Topography,  description  of 10-14 

Triangulation  stations,  description  of 11-13 

location  of,  map  showing 11 

Trout  Run,  coal  on 68-69,96 

coal  on,  section  of 96 

figure  showing 66 

Twin  Rocks,  bench  mark  at 14 

coal  at  or  near 80, 81 , 82, 85 , 89-90 

analysis  of 40, 41, 42 

sections  of,  figures  showing 81 , 89 

rocks  at *.  28 

section  at 90 

U. 

Upper  Freeport  coal,  analyses  of 35,40,65-66 

character  and  distribution  of 25, 

35, 48-50, 64-67, 92-93 

coking  of 35 

sections  of 46, 47, 65 

figures  showing 24, 50, 66 

view  of 48 

Upper  Freeport  limestone  member,  character 

and  distribution  of 25, 126-127 

Upper  Freeport  sandstone.  See  Butler  sand- 
stone member. 

Upper  Kittanning  coal,  analyses  of  . .36, 40, 54, 67-68 

character  and  distribution  of 25, 

35-36, 52-54, 56, 67-69, 93-94, 96 

coking  of 36 

sections  of 26,45,96 

figures  showing 24, 55, 68, 93 

views  of 24,48 

V. 

Ventilation,  methods  of 104 

Viaduct  anticline,  description  of 33 

Vintondale,  bench  mark  at 14 

by-product  plant  at 39 

coal  at  or  near 79, 80, 81, 82, 83 

analysis  of. 40, 42 

mining  at,  method  of 105-112 

method  of,  figures  showing 106, 107, 108 

rocks  near 20 

section  near 79,82 

figure  showing 89 

water  supply  of 135 

W. 

Walnut  Grove,  coal  at 54 

coal  at,  section  of,  figure  showing 55 

Walsall,  coal  from,  analysis  of 40, 42 

coal  from,  sections  of,  figures  showing . . . 93, 95 
Walsall  Creek,  coal  on,  section  of,  figure  show- 
ing   93 

Washing  tests,  cost  of 86-87,99 


142 


INDEX 


Page. 

Water  resources,  character  and  distribution 


of 135-136 

Weber,  coal  from 83,90 

coal  from,  analysis  of 41-42 

sections  at 91 

Wehrum,  bench  mark  at 14 

clay  near 113-114,124 

coal  near 22, 79, 80, 83 

analyses  of 37, 41-42, 84, 85, 86, 87, 88 

briquetting  tests  on 87-88 

coking  tests  on 38-39, 85 

producer-gas  tests  on 86 

sections  of,  figure  showing 89 

steaming  tests  on 83-85 

washing  tests  on 86-87 

water  supply  of 135 

Wells,  use  of 135-136 

Wess  farm,  triangulation  stations  on 12 

Westover  Basin,  description  of 34 


Page. 

West  Virginia,  coals  of,  analyses  of 37 

W hite  Ash  coal.  See  Lower  Kittanning  coal. 

Wilmore,  rocks  near 18 

shales  near 115,123 

Wilmore  Basin,  coals  in 26 

coals  in,  sections  of,  figure  showing 66 

description  of 32-33 

section  in 16-17 

Wilmore  sandstone  member,  character  and 

distribution  of. 18 

Wilmore  syncline.  See  Wilmore  Basin. 

Windber,  coals  near 25, 35, 91-95 

coals  near,  analysis  of 41-42 

section  of,  figure  showing 95 

water  supply  of 135 

Windber  district,  coals  of 92-95 

coals  of,  position  of 91-92 

extent  of 91 


O 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


Bulletin  448 


GEOLOGY  AND  MINERAL  RESOURCES 

OF  THE 

NIZINA  DISTRICT,  ALASKA 


BY 

FRED  H.  MOFFIT 

AND 

STEPHEN  R.  CAPPS 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 


1911 


CONTENTS. 


Pago. 

Preface,  by  Alfred  H.  Brooks 7 

Introduction 9 

Location  and  area 9 

Outline  of  geography,  geology,  and  exploration 9 

Climate 13 

Vegetation 15 

Population i 16 

Transportation 16 

Topography 18 

Relief 18 

Drainage 20 

Descriptive  geology 20 

Stratigraphy 20 

Sedimentary  rocks 20 

Rock  types 20 

Triassic  system 21 

Chitistone  limestone 21 

Character  of  the  formation 21 

Distribution 22 

Thickness 23 

Age 23 

McCarthy  shale 28 

Character  of  the  formation 28 

Distribution 28 

Thickness 29 

Age 30 

Jurassic  system 31 

Kennicott  formation 31 

Character  of  the  formation 31 

Distribution 36 

Thickness  37 

Age  and  correlation 38 

Quaternary  system 43 

Preglacial  conditions 43 

Pleistocene  ( “ Glacial  ” ) epoch 43 

Character  and  extent  of  glaciation 43 

Chitina  glacier 45 

Nizina  glacier 46 

Kennicott  glacier 47 

Retreat  of  the  ice 48 

Bench  gravels 49 

‘ Present  stream  gravels 50 

Postglacial  erosion 51 

Rock  glaciers 52 


3 


4 


CONTENTS. 


Descriptive  geology — Continued.  Page. 

Stratigraphy — Continued. 

Igneous  rocks 60 

Triassic  or  pre-Triassic 60 

Nikolai  greenstone 60 

Character  of  the  formation 60 

Petrographic  description 61 

Distribution 61 

Thickness 62 

Age 63 

Jurassic  or  post-Jurassic  igneous  rocks 64 

Quartz  diorite  porphyry  intrusives 64 

Lithologic  character 64 

Petrographic  description 65 

Distribution 66 

Age 66 

Structure 67 

Areal  geology 70 

Historical  geology - 71 

Sedimentary  and  igneous  record 71 

Physiographic  record 74 

Economic  geology 75 

History 75 

Copper 77 

Occurrence  of  the  ores 77 

General  statement 77 

Copper  sulphide  deposits  in  greenstone  and  limestone 78 

Native  copper  associated  with  the  greenstone 79 

Placer  copper 80 

Origin  of  the  copper  deposits 81 

Description  of  properties 83 

Principal  groups 83 

Bonanza  mine 84 

Jumbo  claim 90 

Erie  claim 91 

Independence  claims 92 

Marvellous  and  Bonanza  extension  claims 92 

Nikolai  claim 93 

Westover  claim 95 

Other  prospects 97 

Gold 98 

Production 98 

Source  of  the  gold 98 

Placer  deposits 100 

Dan  Creek 100 

Chititu  Creek 103 

Young  Creek 107 

Index 109 


ILLUSTRATIONS. 


Page. 

Plate  I.  Map  of  the  Copper  and  Chitina  valleys,  showing  location  of 

area  represented  on  the  Nizina  special  map 0 

II.  Nizina  special  map In  pocket 

III.  Geologic  map  of  the  Nizina  district : In  pocket 

IV.  A,  Talus  cones  on  east  side  of  McCarthy  Creek  at  base  of 

limestone  cliffs;  B,  Folded  Triassic  limestone-shale  beds 

on  southwest  side  of  Copper  Creek 18 

V.  Limestone  wall  on  west  side  of  Nizina  River  near  mouth  of 

Chitistone  River 22 

VI.  A,  Bowlders  in  conglomerate  at  base  of  Kennicott  formation 
on  south  branch  of  Nikolai  Creek;  B,  Sandstone  of  Ken- 
nicott formation  on  ridge  south  of  Nikolai  mine 32 

VII.  A and  B,  Unconformity  between  Triassic  and  Jurassic  for- 
mations   36 

VIII.  Rock  glacier  on  McCarthy  Creek  three-fourths  of  a mile 

above  mouth  of  East  Fork 56 

IX.  A,  Rock  glacier  near  head  of  National  Creek ; B,  Head  of 

rock  glacier  on  Little  Nikolai  Creek 56 

X.  A,  Rock  glacier  in  a tributary  of  McCarthy  Creek  northeast 
of  Bonanza  mine ; B,  Detail  of  surface  of  rock  glacier  on 

tributary  of  McCarthy  Creek 58 

XI.  A,  North  end  of  Porphyry  Peak,  showing  inclusions  of  black 
shale  in  porphyry ; B,  Porphyritic  intrusions  in  black 

shale  of  Kennicott  formation  on  McCarthy  Creek 64 

XII.  West  side  of  ridge  at  Bonanza  mine 84 

Figure  1.  Columnar  section  showing  the  formations  represented  on 

the  geologic  map  of  the  Nizina  district 11 

2.  Columnar  section  of  the  basal  part,  of  the  Kennicott  forma- 

tion exposed  on  Nikolai  Creek 31 

3.  Generalized  columnar  section  of  the  Jurassic  sediment  in 

the  Nizina  district 37 

4.  Diagram  showing  the  overlapping  of  lenticular  porphyry 

sills  in  the  black  shales  of  Copper  Creek 65 

5.  Sketch  map  of  the  area  near  the  Bonanza  mine,  showing  the 

limestone-greenstone  contact,  the  location  of  the  richer 
ores  on  the  surface,  and  the  tunnels 87 

6.  Sketch  showing  form  of  ore  body  exposed  in  the  upper  north- 

ern tunnel  at  the  Bonanza  mine 88 


6 


ILLUSTRATIONS. 


Page. 

Figure  7.  Sketch  showing  form  of  ore  body  exposed  in  the  southern 

tunnel  at  the  Bonanza  mine 89 

8.  Sketch  of  the  ore  body  at  the  Jumbo  claim 91 

9.  Sketch  map  of  area  in  vicinity  of  Nikolai  mine 94 

10.  Sketch  map  of  a part  of  Chititu,  Rex,  and  White  creeks, 

showing  the  location  of  claims  and  the  relation  of  bench 
and  stream  gravels 104 

11.  Diagram  showing  the  method  of  operating  hydraulic  giants 

on  Chititu  Creek 100 


PREFACE. 


By  Alfred  H.  Brooks. 


The  completion  in  1908  of  the  reconnaissance  surveys  a of  the  two 
copper  belts  lying  north  and  south  of  the  Wrangell  Mountains 
paved  the  way  for  more  detailed  investigations.  As  the  southern  or 
Chitina  copper  belt  will  be  the  first  one  to  be  developed,  it  was 
appropriate  to  begin  the  detailed  investigation  in  this  field.  The 
funds  available  for  this  work  made  it  possible  to  survey  only  a 
part  of  the  Chitina  belt,  and  after  careful  consideration  it  was  de- 
cided to  take  up  the  work  in  the  Nizina  district.  This  conclusion 
was  based  on  three  considerations:  (1)  The  information  available 
indicated  that  the  Nizina  district  afforded  the  best  opportunities  for 
solving  the  general  geologic  problems  relating  to  the  entire  copper 
belt;  (2)  the  mining  developments  of  this  part  of  the  district  were 
more  extensive  than  elsewhere  in  the  belt,  which  gave  both  better 
opportunities  for  observations  on  the  occurrence  of  the  ores  and 
greater  promise  of  soon  reaching  a productive  basis;  (3)  investiga- 
tion of  this  field  made  it  possible  to  cover  a placer  district  long  pro- 
ductive in  a small  way  and  giving  promise  of  larger  output. 

The  descriptions  set  forth  in  this  report  apply  to  only  about  one- 
fourth  of  the  Chitina  copper  belt,  but  the  conclusions  advanced  as 
to  occurrence  of  the  ores  will,  it  is  believed,  have  value  to  the  entire 
district.  If  the  developments  in  the  Chitina  Valley  continue,  as  is 
expected,  further  surveys  will  be  undertaken  as  soon  as  circumstances 
permit. 

The  cost  of  detailed  geologic  maps  is  much  increased  by  the  fact 
that  they  must  be  preceded  by  detailed  topographic  surveys.  The 
Nizina  region  was  surveyed  by  D.  C.  Witherspoon  in  1908,  and  the 
resulting  map,  which  is  an  excellent  piece  of  work  done  under  very 
adverse  conditions,  accompanies  this  report  (PI.  II,  in  pocket)  and 
adds  much  to  its  value. 


a Moffit,  F.  H.,  and  Maddren,  A.  G.,  The  mineral  resources  of  the  Kotsina-Chitina  region, 
Alaska  : Bull.  U.  S.  Geol.  Survey  No.  374,  1909  ; Moffit,  F.  H.,  and  Knopf,  Adolph,  The  min- 
eral resources  of  the  Nabesna- White  River  district : Bull.  U.  S.  Geol.  Survey  No.  417, 1910. 

7 


8 


THE  NIZINA  DISTRICT,  ALASKA. 


The  general  geology  of  this  district  as  set  forth  in  the  report  bears 
testimony  to  the  accuracy  of  the  observations  and  deductions  of  the 
earlier  workers  in  this  field.  It  is  a significant  fact  that  the  strati- 
graphic subdivisions,  suggested  by  Oscar  Rohn,  who  did  the  pioneer 
work  in  this  field,  have  found  acceptance  in  the  present  analysis  of 
the  geologic  sequence. 

The  most  important  conclusion  bearing  on  the  economic  geology 
here  presented  is  the  fact  that  the  copper-ore  bodies  appear  to  occur 
chiefly  along  a system  of  cross  fractures  which  are  at  approximately 
right  angles  to  the  greenstone-limestone  contact.  These  fractures 
occur  along  well-defined  faults,  at  least  one  of  which  has  been  traced 
for  a long  distance.  This  may  apply  to  the  entire  Chitina  district 
and  is  worthy  of  consideration  by  the  prospector. 

These  investigations  also  appear  to  indicate  that  the  copper  depos- 
its are  by  no  means  confined  to  the  immediate  vicinity  of  the  lime- 
stone-greenstone contact,  as  has  usually  been  supposed.  Though  the 
most  promising  ore  bodies  thus  far  found  do  occur  in  this  contact, 
evidence  of  strong  mineralization  has  been  found  at  a considerable 
distance  from  it.  Another  important  fact  brought  out  by  this  inves- 
tigation is  the  occurrence  of  auriferous  deposits  in  the  Kennicott 
formation  (Jurassic). 

This  report,  although  far  more  complete  than  any  other  report  pre- 
viously published  on  the  district,  is  b}^  no  means  exhaustive.  With 
the  progress  of  mining  many  facts  will  be  ascertained  which  will 
make  possible  more  definite  statements  on  the  geology  of  the  mineral 
deposits.  If  the  district  develops  into  a great  copper  producer,  a 
detailed  study  of  the  mining  geology  should  be  undertaken  similar 
to  those  made  of  many  of  the  mining  camps  of  the  Western  States. 


U . S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  I 


MAP  OF  THE  COPPER  AND  CHITINA  VALLEYS,  SHOWING  LOCATION  OF  AREA  REPRESENTED  ON  NIZINA  SPECIAL  MAP. 


•TIN  448  PLATE 


GEOLOGY  AND  MINERAL  RESOURCES  OF  THE  NIZINA 
DISTRICT,  ALASKA. 


By  Fred  H.  Moffit  and  Stephen  R.  Capps. 


INTRODUCTION. 

LOCATION  AND  AREA. 

The  Nizina  district  takes  its  name  from  Nizina  River,  a northern 
branch  of  Chitina  River,  and  lies  in  the  eastern  part  of  the  Copper 
River  drainage  basin.  Its  position  with  reference  to  the  coast  and 
the  Canadian  boundary  is  shown  on  Plate  I,  opposite.  That  portion 
of  it  to  which  the  following  descriptions  are  confined  is  included 
between  parallels  61°  12'  and  61°  37'  north  latitude  and  meridians 
142°  22'  and  143°  west  longitude  and  is  represented  on  the  Nizina 
special  map.  (See  PI.  II,  in  pocket.)  The  area  mapped,  however, 
is  irregular  in  outline  and  only  300  square  miles  in  extent,  so  that 
it  comprises  little  more  than  one-half  of  the  quadrangle  indicated. 

OUTLINE  OF  GEOGRAPHY,  GEOLOGY,  AND  EXPLORATION. 

Chitina  River  rises  in  the  high  snow-covered  mountains  northwest 
of  Mount  St.  Elias  and  adjacent  to  the  international  boundary  line 
and  flows  westward  between  the  Chugach  and  the  Wrangell  moun- 
tains till  it  unites  with  Copper  River  at  a point  100  miles  from  the 
coast.  (See  PI.  I.)  Most  of  its  waters,  however,  are  derived  through 
its  northern  tributaries  from  the  snow  fields  of  the  Wrangell  group. 
Nizina  River  is  the  largest  of  these  tributaries.  It  drains  the  south- 
eastern part  of  the  Wrangell  Mountains  and  a small  part  of  the  area 
between  Chitina  River  and  the  head  of  White  River.  From  its  prin- 
cipal source  in  Nizina  Glacier  it  flows  southward  for  15  miles  and 
then  turns  abruptly  to  the  west  and  continues  in  that  direction  20 
miles  farther  before  joining  the  Chitina.  It  therefore  has  a length 
of  35  miles,  all  minor  curves  and  irregularities  of  its  course  being 
disregarded.  The  big  westward  bend  of  the  river  lies  almost  in  the 
center  of  the  area  covered  by  the  Nizina  special  map. 


9 


10 


THE  NIZINA  DISTRICT,  ALASKA. 


The  two  branches  of  the  Nizina,  with  Chitistone  and  Kennicott 
rivers,  contribute  much  the  greater  part  of  its  waters.  It  is  there- 
fore chiefly  of  glacial  origin.  All  these  streams  are  swift  and 
heavily  laden  with  glacial  debris.  They  have  floored  their  val- 
leys with  broad  gravel  flats,  over  which  they  migrate  from  side  to 
side,  sometimes  in  a single  channel,  sometimes  in  a network  of  chan- 
nels, and,  besides  building  up  their  flood  plains  by  the  addition  of 
new  material,  they  are  continually  cutting  away  and  redepositing 
the  material  already  laid  down.  The  principal  small  streams  shown 
on  the  Nizina  special  map  are  McCarthy  Creek,  a tributary  of  Ken- 
nicott River,  and  Dan,  Chititu,  and  Young  creeks,  eastern  tribu- 
taries of  Nizina  River.  Their  valleys  do  not  show  such  profound 
glacial  erosion  as  the  main  streams,  for  the  ice  masses  that  occupied 
them  were  smaller,  yet  they  nevertheless  underwent  extensive  glacia- 
tion. All  are  characterized  by  broad,  open  valleys  at  their  heads 
and  by  rock  canyons  in  their  lowTer  courses. 

The  Wrangell  Mountains,  although  a more  or  less  distinct  group, 
merge  into  the  St.  Elias  Range  on  the  southeast  and  are  not  there 
sharply  defined  from  them.  They  are  limited  on  the  south  and 
west  and  partly  on  the  north  by  the  valleys  of  Chitina  and  Copper 
rivers,  and  are  separated  from  the  Nutzotin  Mountains  on  the  north- 
east by  a depression  extending  from  the  head  of  Copper  River  to  the 
head  of  White  River.  The  group  trends  in  a northwest-southeast 
direction  and  its  length  is  approximately  double  its  width.  Its 
greatest  diameter  is  about  100  miles.  Half  a dozen  or  more  peaks 
of  unusual  beauty  and  size,  ranging  in  height  from  12,000  to  16,200 
feet,  rise  above  the  rugged  snow-covered  mass  about  them,  and  from 
one  of  these,  Mount  Wrangell,  the  group  received  its  name.  The 
Wrangell  Mountains  were  formed  by  the  erosion  of  a great  mass  of 
Tertiary  and  Recent  lavas  piled  up  on  an  older  surface  of  very 
considerable  relief  and  having  its  greatest  development  in  the  neigh- 
borhood of  Mount  Wrangell  and  Mount  Sanford.  The  southeastern 
limit  of  these  younger  flows  is  probably  somewhere  in  the  vicinity  of 
Skolai  Pass  and  Chitistone  River,  although  it  is  possible  that  they 
may  extend  still  farther  to  the  east.  Thus  the  Wrangell  Mountains 
consist  essentially  of  lava  flows  and  are  distinct  in  their  origin  from 
the  other  mountains  about  them,  all  of  which  are  made  up  principally 
of  deformed  sedimentary  beds.  The  area  shown  on  the  Nizina  special 
map  is  on  the  border  line  between  the  volcanic  flows  of  the  Wrangell 
Mountains  on  the  northwest  and  the  older  sedimentary  formations  of 
the  Chugach  and  St.  Elias  mountains  on  the  south  and  southeast,  but 
the  rock  formations  developed  in  the  area  are  mostly  of  sedimentary 
origin. 


INTRODUCTION. 


11 


Conglomerate. 


Shale  and  sandstone. 


Conglomerate. 

Unconformity. 


^r^-r-rr—  Interbedded  shale 
s and  limestone. 


The  formations  represented  on  the  accompanying  geologic  map 
(PI.  Ill,  in  pocket)  are  shown  in  the  section  forming  figure  1.  At 
the  base  is  the  Nikolai  greenstone,  made  up  of  a great  but  unknown 
thickness  of  basaltic  lava  flows,  many  of  which  are  amygdaloidal. 
On  the  top  of  these  flows  rests  the  Chitistone  limestone,  which  was 
deposited  without  any  interruption  of  structural  uniformity  between 
it  and  the  underlying  rocks.  Its  thickness  exceeds  3,000  feet.  The 
lower  part  of  the  Chitistone  formation  con- 
sists of  thick,  massive  beds  of  gray  lime- 
stone, but  toward  the  top  the  limestone  beds 
become  thinner  and  small  shale  beds  appear 
in  increasing  amount  till  they  finally  pre- 
dominate. The  Chitistone  limestone  thus 
passes  by  transition  through  thin-bedded 
shales  and  limestones  into  a black  shale 
with  only  occasional  thin  limestone  beds. 

Much  of  the  shale  was  removed  by  erosion 
before  the  deposition  of  the  succeeding  for- 
mation, so  that  its  thickness,  though  in 
doubt,  can  not  be  less  than  several  thousand 
feet.  Both  the  Chitistone  limestone  and  the 
conformably  overlying  shales  (McCarthy 
shale)  are  of  Upper  Triassic  age. 

A period  of  uplift  and  erosion  took  place 
after  the  Triassic  black  shales  were  laid 
down  and  was  not  terminated  till  Upper 
Jurassic  time,  when  deposition  began  once 
more.  On  the  upturned  edges  of'  the 
Nikolai  greenstone,  the  Chitistone  lime- 
stone, and  the  overtying  Triassic  shales  a 
great  thickness  of  Upper  Jurassic  sedi- 
ments (Kennicott  formation)  was  deposited. 

They  consist  of  conglomerate,  sandstone, 
and  black  shale,  but  the  shale  predominates 
greatly  over  the  conglomerate  and  the 
sandstone.  The  Jurassic  sediments  attain 
a thickness  of  at  least  7,500  feet.  They  are 
the  youngest  of  the  bed-rock  formations  exposed  within  the  mapped 
area.  The  later  deposits  consist  of  Quaternary  sands,  gravel,  and 
silt,  most  of  which  are  intimately  connected  in  origin  with  the  recent 
glaciation  of  the  country. 

The  Nizina  district  has  been  the  scene  of  igneous  activity  from 
Paleozoic  time  to  the  present.  A great  quantity  of  quartz  diorite 
porphyry  in  the  form  of  sills  and  dikes  was  intruded  into  the 
Jurassic  rocks,  but  for  some  reason  these  intrusives  rarely  appear  in 
the  underlying  formations.  In  some  places  the  porphyritic  intrii- 


Basaltio  lava  flows. 


Figure  1. — Columnar  section 
showing  the  formations  rep- 
resented on  the  geologic  map 
of  the  Nizina  district. 


12 


THE  NIZINA  DISTRICT,  ALASKA. 


sives  are  so  extensively  developed  that  they  predominate  over  the 
shale,  and  the  shale  appears  only  as  great  black  masses  caught  up  in 
the  light-colored  intrusive  rock. 

Folding  in  greater  or  less  degree  has  taken  place  in  all  the  forma- 
tions mentioned,  but  is  far  more  pronounced  in  the  older  ones,  par- 
ticularly the  Triassic  shales,  than  in  the  Jurassic  sediments.  Within 
the  area  of  the  Nizina  special  map  the  greenstone,  limestone,  and 
shale  formations  dip  rather  steeply  to  the  northeast.  The  Jurassic 
rocks,  on  the  other  hand,  are  tilted  to  the  southwest  or  lie  in  broad, 
flat  folds.  All  have  been  faulted  and  show  local  displacements  of 
very  considerable  extent. 

The  earliest  references  to  the  geology  of  the  Chitina  Valley  are 
found  in  the  accounts  of  exploring  expeditions  made  by  Allen  in 
1885  and  by  Schwatka  and  Hayes  in  1891.  Such  accounts,  from  the 
nature  of  the  expeditions,  could  give  only  very  incomplete  informa- 
tion. The  investigations  by  Rohn  in  1899,  however,  laid  the  foun- 
dations of  our  present  knowledge  of  the  geology  of  the  region.  He 
recognized  the  formations  that  have  been  described  and  proposed  the 
names  Nikolai,  Chitistone,  and  Ivennicott.  He  also  applied  the  name 
McCarthy  Creek  shale  to  the  shale  formation  overlying  the  Chiti- 
stone limestone;  but  this  was  not  adopted  by  Schrader  and  Spencer 
in  their  later  work,  since  they  believed  that  the  shale  should  be 
divided  into  a number  of  formations.® 

In  1900  Schrader  and  Spencer  carried  on  a much  more  extended 
investigation  of  the  geology  and  mineral  resources  of  the  Chitina 
Valley,  and  at  the  same  time  a topographic  reconnaissance  map  was 
made  by  Gerdine  and  Witherspoon  which  was  used  as  a base  for  the 
geologic  map.  Two  years  later  (1902)  Mendenhall  visited  the  Kot- 
sina  and  the  Elliott  Creek  copper  prospects,  in  the  western  part  of 
the  Chitina  Valley,  and  published  also  some  brief  statements  concern- 
ing the  Nizina  gold  placers,  although  he  had  no  opportunity  to 
examine  them  in  person.  No  further  geologic  work  in  the  Chitina 
region  was  undertaken  by  the  Federal  Government  till  1907,  when 
interest  in  the  copper  resources  of  the  country  led  to  an  examination 
by  Moffit  and  Maddren  of  all  the  copper  prospects  in  the  valley, 
which  resulted  in  some  additional  information  concerning  its  oreolosrv 
and  the  occurrence  of  both  copper  and  gold.  The  importance  of  the 
district  led  to  the  preparation  of  the  Nizina  special  map  by  Wither- 
spoon in  1908  and  to  the  detailed  geologic  investigations  in  1909, 
whose  results  are  described  in  this  report. 

Many  notes  on  the  copper  prospects,  particularly  the  Bonanza 
mine,  have  appeared  in  the  daily  press  and  in  mining  magazines, 
and  although  most  of  them  had  only  a temporary  value  as  news  a 

° Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion  of 
the  Copper  River  district,  Alaska:  Special  publication  U.  S.  Geol.  Survey,  1001,  note  at 
bottom  of  page  32. 


INTRODUCTION. 


13 


few  are  permanent  contributions  to  the  literature.  An  incomplete 
list  of  papers  on  the  district  follows : 

Allen,  Lient.  Henry  T.  Report  of  an  expedition  to  the  Copper,  Tanana,  and 
Koyukuk  rivers,  in  the  Territory  of  Alaska,  in  the  year  1885.  Washington, 
Government  Printing  Office,  1887. 

Hayes,  C.  Willard.  An  expedition  through  the  Yukon  district : Nat.  Geog. 
Mag.,  vol.  4,  1892,  pp.  117-162. 

Rohn,  Oscar.  A reconnaissance  of  the  Chitina  River  and  Skolai  Mountains : 
Twenty-first  Ann.  Report  U.  S.  Geol.  Survey,  pt.  2,  1900,  pp.  393-440. 

Schrader,  Frank  C.,  and  Spencer,  Arthur  C.  The  geology  and  mineral 
resources  of  a portion  of  the  Copper  River  district,  Alaska  : Special  publication 
of  the  U.  S.  Geol.  Survey,  1901. 

Mendenhall,  Walter  C.,  and  Schrader,  Frank  C.  The  mineral  resources 
of  the  Mount  Wrangell  district,  Alaska : Prof.  Paper  U.  S.  Geol.  Survey  No.  15, 
1903. 

Mendenhall,  Walter  C.  Geology  of  the  central  Copper  River  region, 
Alaska:  Prof.  Paper  U.  S.  Geol.  Survey  No.  41,  1905. 

Moffit,  Fred  H.,  and  Maddren,  A.  G.  The  mineral  resources  of  the  Kotsina 
and  Chitina  valleys,  Copper  River  region : Bull.  U.  S.  Geol.  Survey  No.  345, 
1908,  pp.  127-175.  (This  is  a preliminary  statement  of  results  published  in  a 
more  complete  form  in  Bulletin  374. 

Keller,  Herman  A.  The  Copper  River  district,  Alaska : Eng.  and  Min. 
Jour.,  vol.  85,  No.  26,  June,  1908,  pp.  1273-1278. 

Moffit,  Fred  H.,  and  Maddren,  A.  G.  The  Kotsina-Chitina  region,  Alaska : 
Bull.  U.  S.  Geol.  Survey  No.  374,  1909. 

The  field  work  on  which  the  present  report  and  the  geologic  map 
are  based  was  done  between  July  1 and  September  10,  1909,  or  in  a 
little  less  than  seventy  days.  It  was  greatly  aided  by  a previous 
knowledge  of  the  region  and  by  the  earlier  work  of  Schrader  and 
Spencer,  but  the  time  available  was  too  short  to  permit  an  excursion 
up  Nizina  River  to  determine  the  relation  between  the  Triassic  and 
the  Paleozoic  sediments  on  Skolai  Creek,  or  to  make  a careful  study 
of  the  Kennicott  formation  south  of  Young  Creek.  Both  localities 
merit  careful  investigation  because  of  the  light  they  may  throw  on 
the  stratigraphy  of  the  region.  The  chapter  in  this  report  dealing 
with  the  Quaternary  system  was  written  by  Mr.  Capps,  who  also 
did  the  office  work  on  the  geologic  map.  The  task  of  preparing  the 
remainder  of  the  description  of  general  geology  and  of  economic 
geology  fell  to  the  senior  author. 

CLIMATE. 

The  climate  of  Chitina  Valley  is  pleasanter  in  many  ways  than 
that  of  the  Pacific  coast  region  of  Alaska.  Temperature  variations 
are  far  greater,  but  the  precipitation  is  less  and  the  number  of  cloudy, 
disagreeable  days  is  very  much  smaller.  No  continuous  records  of 
temperature  and  precipitation  are  at  hand,  and  it  is  probable  that 
none  have  been  kept,  although  observations  for  parts  of  several  years 
have  been  made  at  Kennicott  and  were  made  available  through  the 
kindness  of  Mr.  Stephen  Birch. 


14 


THE  NIZINA  DISTRICT,  ALASKA. 


The  Copper  River  region,  of  which  Chitina  Valley  is  a part,  as 
has  been  stated  previously,  is  separated  from  the  Pacific  coast  by  a 
broad  belt  of  mountains  nearly  50  miles  across  and  ranging  in  height 
from  6,000  to  10,000  feet.  This  belt  is  broken  only  by  the  narrow 
canyon-like  valley  of  the  lower  Copper  River,  and  by  its  influence 
on  the  warm  moisture-laden  air  of  the  Pacific  it  becomes  an  important 
factor  in  the  climate  of  Copper  and  Chitina  basins.  Another  factor 
of  importance  is  the  still  loftier  Wrangell  group  of  mountains  on  the 
north. 

The  seasons  of  Copper  River  basin  are  a long  winter  and  a short 
summer,  separated  by  a still  shorter  spring  and  fall.  Spring  comes 
sooner  in  the  upper  Chitina  Valley  than  in  the  Copper  River  valley 
proper,  as  is  shown  by  the  earlier  breaking  up  of  the  ice.  Snow  goes 
from  the  valley  bottoms  by  the  middle  of  May  and  from  the  lower 
hills  by  the  first  of  June,  but  enough  remains  on  the  mountain  sides 
till  the  first  or  middle  of  July  to  hinder  prospecting.  The  summer 
climate  resembles  that  of  some  of  our  Northern  States  in  late  spring. 
Frosts  are  not  expected  from  the  middle  of  June  to  the  middle  of 
July,  but  by  the  first  of  September  the  snow  line  begins  to  descend 
on  the  mountain  sides.  After  the  spring  break-up  the  volume  of 
water  in  the  streams,  particularly  those  fed  by  snow  fields  and 
glaciers,  gradually  increases  until  it  reaches  a maximum  about  the 
middle  of  July;  it  then  decreases  rapidly  as  the  cooler  nights  come 
on.  The  July  period  of  high  water  is  not  the  result  of  increased  pre- 
cipitation but  of  the  warm  weather  and  the  bright  sun  on  the  snow 
fields.  Cloudy  da}^s  alwaj^s  make  a very  appreciable  difference  in 
the  daily  rise  of  the  glacier  streams.  Sometimes,  however,  the  rivers 
are  flooded  by  unusually  heavy  rains  and  occasionally  in  winter  by 
the  breaking  out  of  water  confined  in  the  glaciers.  This  took  place 
in  the  Kennicott  Glacier  early  in  1909.  During  a period  of  unusually 
cold  weather  the  outlet  of  the  subglacial  stream  known  as  the  “ pot- 
hole ” was  closed  and  the  water  backed  up  under  the  glacier  till  the 
pressure  was  so  great  that  the  ice  could  not  resist  it.  The  water  burst 
forth  from  a new  outlet  and  flooded  the  Kennicott  and  Chitina 
rivers,  tearing  up  the  ice  and  piling  it  in  confusion.  Fortunately 
no  one  was  freighting  on  the  river,  and  the  new  ice  which  formed 
afterward  gave  the  best  sledding  ever  known  by  freighters  on  the 
Chitina.  A similar  flood  caused  by  the  breaking  out  of  confined 
waters  from  Nizina  Glacier  took  place  a few  years  previously.  The 
high  water  of  July  makes  the  fording  of  Nizina  River  difficult  and 
at  times  dangerous,  but  this  difficulty  decreases  in  August,  and  by 
the  first  of  September  it  is  ended.  Temperatures  low  enough  to  allow 
standing  water  to  freeze  are  usual  in  the  latter  part  of  August,  and 
early  in  September  the  glaciers  cease  to  be  active  and  the  streams 
are  clear  and  low. 


INTRODUCTION. 


15 


Temperatures  of  30°,  40°,  or  even  50°  below  zero  are  experienced 
in  winter,  and  the  snowfall  is  heavy,  although  much  less  than  on  the 
coast. 

Observations  at  Kennicott,  at  the  mouth  of  National  Creek,  and 
at  the  Bonanza  mine,  a little  more  than  2^  miles  away  and  4,000 
feet  higher,  showed  that  the  temperature  at  the  mine  during  the  cold- 
est weather  was  always  considerably  higher  than  at  the  lower  camp. 

The  winter  of  1908-9  was  unusual  because  of  its  low  temperatures 
and  light  snowfall.  It  resulted  from  these  conditions  that  the 
streams  were  in  places  frozen  to  the  bottom,  and  the  water,  breaking 
out  above,  ran  down  over  the  top  and  froze  to  a great  thickness. 
Some  of  the  so-called  glaciers  on  Chititu  Creek  had  a thickness  of 
15  or  20  feet  and  did  not  melt  a^ay  till  early  in  the  following  July, 
thus  seriously  interfering  with  placer  mining.  Such  conditions  are 
common  enough  in  the  streams  of  northern  Alaska  but  are  unusual 
in  the  Nizina  district. 

VEGETATION. 

In  this  region,  as  in  many  other  parts  of  Alaska,  vegetation  flour- 
ishes in  a way  that  would  be  surprising  to  those  who  think  of  the 
country  only  as  a region  of  continual  cold  and  ice.  The  growing 
season  is  short,  but  the  summer  days  are  warm  and  much  longer  than 
in  lower  latitudes,  so  that  in  the  few  favorable  weeks  plants  grow 
rapidly.  Grass  comes  up  as  soon  as  the  snow  goes  and  by  the  first 
or  middle  of  June  there  is  good  feed  for  horses  in  favorable  places. 
It  is  not  abundant  in  the  lower  valley  bottoms,  even  in  midsummer, 
and  the  best  of  it  is  found  at  or  above  timber  line.  There  is  good 
feed  in  the  upper  part  of  all  the  small  valleys.  A small  leguminous 
plant,  locally  called  “ pea  vine,”  grows  on  the  gravel  bars  and  in  the 
fall  and  late  summer  makes  excellent  forage.  It  is  nourishing,  and 
horses  are  so  fond  of  it  that  they  will  leave  almost  anything  else  to  get 
it.  Grass  loses  its  nourishing  qualities  as  soon  as  the  frost  strikes  it, 
and  for  this  reason  miners  and  prospectors  start  their  horses  to  the 
coast  about  the  first  of  September. 

All  the  lower  mountain  slopes  of  the  Nizina  district  and  all  the 
valley  bottoms  except  the  flood  plains  of  streams  are  covered  with 
spruce  timber.  The  upper  limit  of  timber  ranges  from  2,500  to  4,000 
feet  above  sea  and  is  highest  on  the  gentle  and  rounded  slopes  away 
from  the  glaciers,  such  as  the  south  slope  of  the  ridge  west  of  Rex 
Creek  and  on  Sourdough  Hill.  Timber  suitable  for  lumber  grows 
on  the  lower  ground.  The  best  of  it  is  found  on  the  flats  south  of 
Nizina  River,  from  Dan  Creek  to  Young  Creek,  in  the  drier  ground 
at  the  base  of  the  hill  slopes.  Some  of  the  trees  reach  a diameter 
of  18  inches  and  are  tall  enough  to  furnish  two  16-foot  cuts.  Be- 
sides the  spruce,  there  are  cottonwood  and  birch,  but  these  have 


16 


THE  NIZINA  DISTRICT,  ALASKA. 


little  value  for  lumber.  A heavy  growth  of  alders  is  usually  found 
about  timber  line.  Willows  are  present  in  the  valleys,  but  are  far 
less  abundant  in  variety  and  amount  than  in  northern  Alaska.  The 
“ devilclub,”  so  troublesome  in  the  coast  region,  is  found  occasionally 
in  the  Nizina  district  also. 


POPULATION. 

During  the  early  days  of  the  Nizina  gold  excitement  the  white 
population  of  the  district  amounted  to  several  hundred  persons,  but 
this  number  quickly  decreased,  asns  usual  in  such  stampedes.  There 
are  no  accurate  records  of  the  number  of  early  comers.  Some  of  them 
were  of  the  “ hanger-on  ” class  and  stayed  only  long  enough  to  learn 
that  the  district  had  little  to  offer  them.  The  later  population  has 
been  a variable  one,  but  for  the  last  two  or  three  years  it  probably 
has  not  been  far  from  100.  Most  of  this  number  were  employed  in 
the  gold  placers  of  Chititu  and  Dan  creeks  and  the  rest  were  pros- 
pecting for  copper.  With  the  completion  of  the  railroad  and  the 
beginning  of  mining  at  Kennicott  and  the  increased  activity  in  the 
gold-producing  streams  that  will  come  with  better  transportation 
the  white  population  will  increase.  There  is  no  permanent  native 
population.  Nizina  River  valley  was  the  hunting  ground  of  Chief 
Nikolai,  and  his  house  was  near  the  mouth  of  Dan  Creek,  but  since 
hffe  death  several  years  ago  superstition  has  kept  his  followers  from 
returning  there  until  within  the  last  two  summers.  The  perma- 
nent dwellings  of  the  Indians  are  on  Copper  River,  where  they  spend 
most  of  the  winter  and  where  they  fish  in  summer.  It  seems  to  have 
been  the  custom  of  many  to  leave  the  fishing  ground  only  during  the 
time  of  the  fall  hunting  or  in  the  trapping  season. 

TRANSPORTATION. 

To  provide  satisfactory  means  and  routes  of  transportation  has 
been  from  the  beginning  the  most  serious  difficulty  the  prospectors 
in  Chitina  Valley  have  had  to  meet.  Up  to  the  present  time  all 
supplies  and  equipment  for  the  Nizina  district  have  been  brought 
from  Valdez  in  winter  by  sled.  The  route  usually  followed  in 
freighting  is  from  Valdez  to  Tonsina  over  the  Government  trail,  then 
by  way  of  Tonsina,  Copper,  Chitina,  and  Nazina  rivers  to  the  desti- 
nation. Occasionally,  however,  this  route  has  been  varied  by  cross- 
ing Marshall  Pass  at  the  head  of  Lowe  River  and  following  Tasnuna 
and  Copper  rivers  to  the  mouth  of  the  Chitina ; but  this  latter  route 
was  given  up  because  of  the  difficulties  encountered  on  Tasnuna 
River  and  of  the  fact  that  the  Government  trail  to  Fairbanks 
is  kept  open  all  winter  by  the  regular  travel.  The  great  advantage 
of  the  route  lay  in  the  ability  to  haul  very  heavy  loads  on  the 


INTRODUCTION. 


17 


smooth  ice  of  Copper  River,  thus  saving  time  and  horse  feed,  the  two 
great  items  of  expense,  on  this  part  of  the  trip.  This  route  prob- 
ably would  have  been  used  exclusively  for  freighting  to  Chitina 
Valley  if  a good  trail  down  Tasnuna  River  had  been  available  for 
travel. 

The  time  consumed  in  carrying  large  outfits  from  Valdez  to  the 
Nizina  district  is  from  two  to  three  months.  The  cost  of  freighting 
has  varied  from  slightly  less  than  7 cents  to  30  cents  per  pound,  de- 
pending on  the  size  of  the  outfit  and  the  condition  of  the  trail.  The 
lower  figure  of  cost  is  an  exceptional  one  and  is  not  possible  under 
any  other  than  the  most  favorable  conditions.  Probably  about  10 
cents  per  pound  is  an  average  cost  for  the  larger  companies  when  the 
trail  is  good. 

Summer  travel  is  over  a route  different  from  that  followed  in 
winter.  The  summer  trail  leaves  the  Government  trail  at  Tonsina 
and  crosses  Copper  River  at  the  mouth  of  Tonsina  River.  From 
there  it  passes  to  the  north  side  of  Chitina  Valley,  entering  the  moun- 
tains by  way  of  Kuskalana  River  and  crossing  Kuskalana  and  Fourth 
of  July  passes  to  Ivennicott  Glacier  and  River.  No  freighting  is  done 
on  the  summer  trail,  but  the  mail  goes  in  over  it  twice  each  month. 

Within  the  Nizina  district  trails  connect  the  various  camps  and 
enable  the  miners  to  travel  from  one  to  another  without  serious  diffi- 
culty, although  there  is  little  communication  between  them  during 
the  working  season.  The  trails  are  all  shown  on  the  topographic 
map  and  need  not  be  described  in  detail.  The  one  most  traveled  is 
that  over  Sourdough  Hill  from  McCarthy  Creek  to  Chititu  and  Dan 
creeks.  Because  it  is  less  swampy,  it  is  used  by  many  in  preference 
to  the  lower  trail  around  the  west  end  of  the  hill,  but  the  hill  is 
steep  and  the  climb  is  hard.  One  great  difficulty  with  this  trail  is 
the  necessity  of  fording  Nizina  River.  A proposal  to  bridge  the  river 
at  a point  several  miles  below  the  present  fording  place  will  probably 
be  carried  out  in  the  near  future. 

It  is  seen  from  the  figures  previously  given  that  the  cost  of  trans- 
portation is  a heavy  tax  on  all  work  done  in  the  Nizina  district. 
This  expense  has  not  only  hindered  copper  prospecting  but  has  de- 
layed the  installation  of  placer  mining  machinery  also.  This  bur- 
den will  be  much  lightened  in  a short  time,  however,  for  railroad 
communication  with  the  coast  is  promised  early  in  1911.  Construc- 
tion work  on  the  Copper  River  and  Northwestern  Railway  was 
commenced  under  the  present  management  at  Cordova  in  1908  and 
since  that  time  has  been  pushed  as  rapidly  as  conditions  permitted. 
In  1908  the  tracks  were  advanced  from  Cordova  to  within  10  or  12 
miles  of  Abercrombie  Rapids,  although  the  lower  steel  bridge  over 
Copper  River  was  not  erected  till  the  following  spring.  In  1909 
the  piers  for  a second  bridge,  at  the  river  crossing  between  Childs 
70648°— Bull.  448—11 2 


18 


THE  NIZINA  DISTRICT,  ALASKA. 


Glacier  and  Miles  Glacier  Lake,  were  built  and  the  tracks  were  ad- 
vanced to  Tiekel  River.  With  the  completion  of  this  part  of  the 
road  most  of  the  slow  and  difficult  work  was  ended  and  there  re- 
mained only  90  miles  of  track  construction  to  reach  Kennicott.  This 
includes  a third  bridge  over  Copper  River,  between  the  mouths  of 
Chitina  and  Kotsina  rivers,  where  it  is  proposed  to  place  a tempo- 
rary pile  bridge  while  the  construction  of  piers  for  the  permanent 
bridge  is  going  on.  The  building  of  the  railroad  has  not  involved 
any  unusually  difficult  construction  problems  for  modern  railroad 
engineering,  and  the  greatest  obstacles  to  operation  will  doubtless 
arise  from  weather  conditions.  Along  Copper  River  the  tracks  are 
particularly  exposed  to  obstruction  by  snowslides,  and  adequate,  pro- 
vision for  their  protection  will  have  to  be  made.  Above  Abercrombie 
Rapids  the  tracks  follow  the  river  bank  on  the  debris-covered  edge 
of  Baird  Glacier.  The  ice  is  overlain  by  a thin  coating  of  loose 
rock  and  is  overgrown  with  alders.  It  appears  to  have  no  motion, 
but  it  is  probable  that  more  or  less  melting  goes  on  and  that  the 
tracks  will  require  more  attention  and  repair  than  in  other  places. 
Some  have  expressed  uncertainty  concerning  the  effect  of  the  terri- 
ble winter  winds  that  sweep  down  the  lower  part  of  Copper  River 
valley  and  have  even  predicted  that  they  would  prevent  the  running 
of  trains,  but  such  difficulties  have  been  overcome  elsewhere  and  prob- 
ably will  be  here.  Railroad  communication  with  the  coast  promises 
greater  aid  in  the  development  of  the  Copper  River  valley  than  any 
other  single  enterprise  yet  undertaken. 

TOPOGRAPHY. 

BELIEF. 

The  Nizina  district  has  been  described  as  situated  at  the  south- 
eastern border  of  the  Wrangell  Mountains,  in  the  region  where  this 
group  merges  into  the  Coast  Range  Mountains  to  the  east  and  south. 
The  mapped  area  does  not  extend  far  enough  north  or  east  to  take 
in  any  of  the  larger  snow  fields  or  glaciers  or  to  include  the  highest 
mountains  of  the  Wrangell  group  or  Coast  Range,  although  peaks  of 
7,000  or  8,000  feet  are  shown.  To  the  southeast  is  the  broad  low- 
land formed  by  the  junction  of  Chitina  and  Nizina  valleys.  The 
map'  (PL  II,  in  pocket)  shows  as  the  major  features  of  relief  two 
mountain  areas  separated  by  the  valley  of  Nizina  River,  but  other 
topographic  forms  are  even  as  striking  as  these,  particularly  the 
steep,  straight  valley  Avails,  the  deep  gulches  tributary  to  Young 
Creek,  and  the  peculiar  Avormlike  rock  glaciers. 

Three  geologic  elements  are  involved  in  the  relief — the  high  moun- 
tain masses,  the  gravel-covered  lowlands,  and  the  gravel  benches  or 
terraces.  Glacial  erosion  and  the  character  of  the  rock  formation  have 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  IV 


A.  TALUS  CONES  ON  EAST  SIDE  OF  McCARTHY  CREEK,  AT  BASE  OF  LIMESTONE  CLIFFS. 

See  page  1 9. 


B.  FOLDED  TRIASSIC  LIMESTONE  AND  SHALE  BEDS  ON  SOUTHWEST  SIDE  OF  COPPER  CREEK. 

See  page  28. 


TOPOGRAPHY. 


19 


been  strikingly  effective  in  giving  form  to  the  mountains.  The  work 
of  the  ice  in  straightening  and  steepening  valley  walls  is  conspicuous 
on  Chitistone  River  and  the  adjacent  part  of  Nizina  River  and  on 
the  upper  part  of  McCarthy  Creek.  It  is  also  seen  in  the  numerous 
cirque  valleys  in  which  most  of  the  streams  head.  McCarthy  Creek 
is  a typical  example  of  a glaciated  valley  in  this  district.  Its  upper 
part  is  a broad,  open,  U-shaped  valley  with  gravel  floor.  Its  lower 
part  is  a succession  of  rock  canyons  with  high  gravel  terraces.  These 
features,  except  the  gravel  terraces,  are  characteristic  of  every 
glaciated  valley  of  the  region  and  are  probably  the  result  of  rapid 
head  valley  glacial  erosion  and  the  effort  of  the  stream  to  establish 
a more  advantageous  grade  after  the  melting  of  the  ice. 

Different  kinds  of  rock  were  affected  in  different  degrees  by  the 
glacial  ice  and  by  subsequent  erosion.  The  massive  Chitistone  lime- 
stone forms  precipitous  cliffs  and  tall  spires,  as  on  Dan  Creek,  Chiti- 
stone and  Nizina  rivers,  McCarthy  Creek,  and  at  Bonanza  mine. 
The  greenstone  slopes  are  not  so  steep  and  are  more  uniform  in  sur- 
face contour;  they  rarely  form  perpendicular  walls  such  as  are  com- 
mon in  the  limestone  exposures.  The  shales  give  smooth,  rounded 
outlines  where  they  have  undergone  glacial  erosion  and  sharp,  jagged 
peaks  and  ridges  with  steep,  bare  slopes  where  they  have  been  sub- 
jected to  attack  by  weather  alone.  These  two  features  are  seen  in 
the  shale  area  south  of  Dan  Creek.  Between  Dan  Creek  and  White 
Gulch  the  shale  mountains  are  characterized  by  angular  outlines  and 
bare  slopes,  but  south  of  Chititu  Creek  the  same  shales  were  over- 
ridden by  the  ice  streams  from  Chitina  Valley  and  present  smooth, 
rounded  contours.  This  feature,  however,  has  been  modified  by 
intense  postglacial  erosion,  with  the  production  of  such  topographic 
forms  as  Blei  Gulch  and  the  deep  gashes  cut  by  tributaries  of  Young 
Creek.  A different  topographic  form,  dependent  on  the  structure  of 
the  upper  shale  formation,  is  the  flat  top  of  the  ridge  on  the  west  side 
of  Nizina  River  directly  opposite  the  mouth  of  the  Chitistone.  It  is 
due  to  the  almost  horizontal  position  of  the  sandstone  beds  that  form 
the  base  of  the  Kennicott  in  this  locality. 

Talus  deposits  cover  the  lowest  mountain  slopes  and  reach  their 
greatest  development  at  the  bases  of  large  porphyry  exposures  and 
limestone  cliffs.  In  this  connection  it  should  be  said  that  the  occur- 
rence of  a small  proportion  of  porphyry  in  talus  slopes  and  rock 
glaciers  is  usually  sufficient  to  obscure  other  kinds  of  rock.  Talus 
fans  of  noticeable  symmetry  have  been  built  up  below  gulches  in 
the  limestone  formation  east  of  McCarthy  Creek  (PL  IV,  A)  and 
north  of  Chitistone  River.  The  peculiar  detrital  accumulations  here 
called  rock  glaciers  are  confined  to  the  high  mountainous  parts  of 
the  district  but  are  widely  distributed  in  the  mapped  area.  They 
are  described  in  the  discussion  of  Quaternary  deposits. 


20  THE  NIZTNA  DISTRICT,  ALASKA. 

The  second  important  element  in  the  relief  of  the  district  is  the 
gravel-covered  valley  lowland  areas.  Their  distribution  is  readily 
seen  on  the  map.  They  represent  the  accumulated  deposits  of  present 
glacial  erosion  and  the  reworked  deposits  of  former  glaciation,  to- 
gether with  the  contributions  of  present  stream  erosion.  With  the 
older  bench  gravels  they  occupy  fully  one-third  of  the  mapped  area. 
The  bench  gravels,  wdiich  are  of  glaciofluvial  origin,  are  most  con- 
spicuous about  the  mouth  of  Dan  Creek,  the  lower  parts  of  Chititu 
and  Young  creeks,  and  on  McCarthy  Creek,  but  are  present  in  other 
places  also. 

DRAINAGE. 

Nearly  all  the  larger  streams  of  the  Nizina  district  originating 
within  the  mountain  area  head  in  glaciers,  and  those  that  do  not 
thus  head  nevertheless  receive  much  of  their  water  from  melting  snow 
banks  throughout  all  or  part  of  the  year.  All  the  streams  are  swift 
and  subject  to  rapid  variations  in  quantity  of  water  flowing  in  them. 
Nizina  Kiver  falls  600  feet  in  19  miles  within  the  mapped  area,  or  at 
the  rate  of  31.5  feet  per  mile.  McCarthy  Creek  has  a grade  of  100 
feet  per  mile  and  Chititu  Creek  180  feet  per  mile  in  their  lower 
courses. 

In  contrast  with  the  well-drained  mountain  areas,  the  lowlands  are 
swampy  and  dotted  with  numerous  ponds  and  lakes.  They  are  cov- 
ered with  an  inferior  growth  of  spruce  and  with  moss  that  acts  like 
a sponge  to  hold  water  and  prevent  its  rapid  run-off.  The  surplus 
water  from  the  lakes  is  carried  away  in  sluggish  clear-water  streams. 
These  features  are  characteristic  of  the  southwest  part  of  the  mapped 
area.  Trails  in  such  country  are  often  almost  impassable  for  horses 
in  summer,  and  for  that  reason  they  keep  to  the  gravel  bars  or  the 
ridges. 

DESCRIPTIVE  GEOLOGY. 

STRATIGRAPHY. 

SEDIMENTARY  ROCKS. 

ROCK  TYPES. 

It  has  already  been  stated  that  the  Nikolai  greenstone  is  the  oldest 
rock  formation  exposed  in  the  Nizina  district  and  that  it  is  conform- 
ably overlain  by  the  Chitistone  limestone  and  a shale  formation 
(McCarthy  shale),  both  of  which  are  of  Triassic  age.  It  was  further 
stated  that  a great  thickness  of  shale  of  Jurassic  age — the  Ivennicott 
formation — rests  unconformably  upon  the  upturned  edges  of  the 
greenstone,  limestone,  and  shale;  that  these  formations,  particularly 
the  Ivennicott,  were  intruded  by  light-colored  porphyritic  igneous 
rocks ; and  that  the  most  recent  deposits  of  the  district  are  unconsoli- 
dated gravels  of  Quaternary  age. 


SEDIMENTARY  ROCKS. 


21 


The  Nikolai  greenstone,  because  of  its  relation  to  the  Chitistone 
limestone,  its  importance  as  a geologic  formation,  and  its  structure, 
might  fittingly  be  described  in  connection  with  the  sedimentary 
formations.  Inasmuch,  however,  as  it  is  of  igneous  origin,  its  descrip- 
tion will  be  taken  up  later  in  its  proper  place  in  the  account  of  the 
igneous  rocks. 

TRIASSIC  SYSTEM. 

CHITISTONE  LIMESTONE. 

CHARACTER  OF  THE  FORMATION. 

The  name  Chitistone  was  applied  by  Rohn  to  the  great  Triassic 
limestone  of  the  Nizina  district  because  he  found  the  limestone  best 
developed  along  the  Nizina  in  the  vicinity  of  the  mouth  of  Chiti- 
stone River.  This  name  was  later  adopted  by  Schrader  and  Spencer 
and  has  since  come  into  general  use.  The  Chitistone  limestone  is  a 
conspicuous  formation  occurring  all  along  the  south  flanks  of  the 
Wrangell  Mountains  from  Kotsina  River  to  Dan  Creek  and  prob- 
ably extending  into  the  valley  of  the  upper  Chitina.  In  the  Nizina 
district  the  lower  part  of  the  Chitistone  formation  is  made  up  of 
thick,  massive  beds  of  a dark-gray  or  bluish-gray  color  but  weather- 
ing to  a lighter  gray  on  the  surface.  The  upper  part,  on  the  other 
hand,  is  made  up  of  thinner  beds,  and  this  thinness  increases  toward 
the  top.  A slight  difference  in  chemical  composition  between  the 
upper  and  the  lower  parts  of  the  Chitistone  limestone  is  indicated 
by  the  brownish-yellow  weathering  of  the  upper  part.  Changing 
conditions  of  sedimentation  are  indicated,  too,  in  a more  noticeable 
way  by  the  appearance  of  thin  shale  beds  at  the  top  of  the  formation. 
This  limestone  is  the  oldest  of  the  sedimentary  formations  exposed 
within  the  mapped  area  and  lies  on  the  Nikolai  greenstone  conform- 
ably, exactly  as  if  both  were  sedimentary  formations  deposited  in 
the  same  sea  and  the  limestone  had  been  laid  down  on  the  greenstone 
before  any  movement  or  disturbance  had  taken  place  in  the  green- 
stone. This  conformable  relation  holds  true  wherever  the  contact 
has  been  examined,  although  in  many  places  it  is  found  that  there 
has  been  movement  of  the  two  formations  along  this  contact  surface. 
In  several  places  a bed  of  red  and  green  shale  with  a maximum  thick- 
ness of  about  5 feet  was  found  to  intervene  between  the  limestone 
and  the  greenstone,  but  it  is  not  known  whether  the  shale  is  widely 
distributed  or  not,  since  the  limestone-greenstone  contact  is  nearly 
everywhere  covered  with  talus.  The  shale  is  present  in  the  vicinity 
of  Bonanza  mine  and  on  Kennicott  Glacier. 

Excellent  sections  of  the  Chitistone  limestone  are  seen  on  the  west 
side  of  Nizina  River,  opposite  the  mouth  of  Chitistone  River,  and  on 
McCarthy  Creek.  On  McCarthy  Creek  the  lower  part  of  the  forma- 


22 


THE  NIZINA  DISTRICT,  ALASKA. 


tion,  which  dips  about  30°  NE.,  consists  of  massive  beds  of  bluish- 
gray  limestone,  making  up  approximately  three-fifths  of  the  total 
thickness.  Above  this  lower  massive  portion  is  a succession  of  more 
thinly  bedded  limestone  strata  weathering  a rusty-yellow  color  and 
making  up  the  remaining  two-fifths  of  the  formation.  The  thick- 
ness of  individual  beds  decreases  from  the  base  toward  the  top,  as 
has  been  stated,  and  near  the  top  thin  beds  of  black  shale  make  their 
appearance.  Then  comes  an  indefinite  thickness,  approximately  300 
feet,  of  thin-bedded  limestone  and  shale  overlain  in  turi^  by  a great 
thickness  of  black  shale,  which  Rohn  called  the  McCarthy  Creek 
shale.®  It  is  thus  seen  that  there  is  a transition  from  the  bedded 
limestones  below  through  interbedded  thin  limestones  and  shales  to 
shale  above,  and  it  is  readily  understood  that  difficulty  arises  in 
choosing  a definite  dividing  plane  between  these  two  formations. 

The  section  on  Nizina  River  shows  the  same  features  as  that  on 
McCarthy  Creek,  but  here  the  whole  syncline  is  exposed,  revealing 
the  steep  northward  dip  on  the  south,  the  horizontal  bedding  in  the 
middle,  and  the  gentle  southward  dip  on  the  north.  The  bedding 
features  are  well  shown  in  the  center  of  the  syncline  for  the  whole 
succession  from  base  to  overlying  shales.  (See  Pl.  V.) 

DISTRIBUTION. 

The  Chitistone  limestone  occupies  a narrow  band  along  the  north- 
eastern edge  of  the  mapped  area,  extending  southeastward  from 
Kennicott  Glacier  (at  the  northern  limit  of  the  area)  to  the  head  of 
Copper  Creek.  The  dip  of  the  limestone  along  its  southern  bound- 
ary is  to  the  northeast  and  decreases  from  approximately  30°  in  the 
vicinity  of  Kennicott  Glacier  and  McCarthy  Creek  to  only  a few 
degrees  on  Dan  and  Copper  creeks.  It  results  from  this  that  the 
width  of  the  limestone  belt  is  much  less  at  the  glacier  and  on  Mc- 
Carthy Creek  than  on  Dan  Creek.  The  limestone  belt  has  a width 
of  slightly  more  than  1 mile  on  the  ridge  between  McCarthy  Creek 
and  East  Fork,  which  is  probably  less  than  its  width  at  any  place 
between  McCarthy  Creek  and  Kennicott  Glacier.  East  of  Nizina 
River  the  limestone  caps  the  mountains  between  Dan  Creek  and 
Chitistone  River  in  the  form  of  a broad,  shallow  syncline  fully  5 
miles  wide.  The  continuity  of  limestone  exposures  is  interrupted 
in  many  places  by  valley  gravel  and  talus  deposits,  but  aside  from 
separate  limestone  areas  produced  in  this  way  there  are  a number 
of  small  detached  areas  wffiose  separation  from  the  principal  lime- 
stone masses  represented  on  the  map  is  due  to  other  causes.  Such 
an  area  is  seen  at  the  head  of  Nikolai  Creek  and  owTes  its  isolation  to 
the  fact  that  the  overlying  Kennicott  formation  has  been  only  partly 
eroded.  If  all  of  the  conglomerate  and  sandstone  of  the  Kennicott 

" Rohn,  Oscar,  A reconnaissance  of  the  Chitina  River  and  the  Skolai  Mountains,  Alaska  : 
Twenty-first  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  2,  1900,  p.  426. 


LIMESTONE  WALL  ON  WEST  SIDE  OF  NIZINA  RIVER  NEAR  MOUTH  OF  CHITISTONE  RIVER. 


SEDIMENTARY  ROCKS. 


23 


were  removed,  the  small  limestone  area  would  be  found  to  be  part  of 
the  larger  area  to  the  east.  Another  isolated  area  lies  south  of  Dan 
Creek,  but  in  this  case  the  limestone  was  separated  from  the  main 
limestone  mass  to  the  north  and  reached  its  present  position  through 
faulting. 

THICKNESS. 

The  two  localities  on  Nizina  River  and  McCarthy  Creek  afford 
favorable  opportunities  for  measuring  the  thickness  of  the  Chitistone 
limestone,  since  in  both  places  the  whole  formation  is  present.  One 
element  of  uncertainty  presents  itself,  however — the  difficulty  of 
choosing  the  somewhat  arbitrary  plane  to  separate  the  limestone  from 
the  overlying  shales;  yet,  since  the  intervening  thin-bedded  shale- 
limestone  succession  is  probably  less  than  300  feet  thick,  the  error  in 
measurement,  and  the  results  are  the  same  as  on  Nizina  River.  A 
5 per  cent,  as  will  be  seen  later. 

The  base  of  the  limestone  in  the  central  part  of  the  syncline  on 
Nizina  River  is  hidden  by  river  gravels,  but  since  the  curve  of  the 
beds  is  small  and  regular  and  greenstone  is  exposed  along  the  base 
of  the  cliffs  only  a short  distance  north  and  south  of  the  axis  of  the 
syncline,  it  is  evident  that  almost  the  complete  section  of  the  lime- 
stone is  shown  in  one  vertical  column.  This  section  gives  a thickness 
of  3,000  feet  for  the  Chitistone  limestone  in  its  type  locality.  The 
McCarthy  Creek  section  gives  an  almost  equally  good  chance  for 
measurement,  and  the  results  are  the  same  as  on  Nizina  River.  A 
section  north  of  Chitistone  River  gives  a greater  thickness  than  3,000 
feet,  but  as  in  this  locality  the  limestone  has  been  folded  and  faulted 
it  is  believed  that  the  figures  there  are  less  reliable  than  those  first 
given. 

Exposures  of  Chitistone  limestone  extend  westward  to  Kotsina 
River,  less  than  15  miles  from  Copper  River,  but  the  thickness  is 
much  less  than  in  the  Nizina  district  and  in  places  is  not  more  than 
200  or  300  feet.  No  evidence  has  been  collected  to  show  that  the 
limestone  becomes  progressively  thinner  from  the  east  toward  the 
west  in  Chitina  Valley,  and,  although  that  may  be  the  case,  the  de- 
creased thickness  in  the  valleys  of  Kotsina  River  and  Elliott  Creek 
may  be  due  to  erosion  before  deposition  of  the  Kennicott  formation 
took  place. 

AGE. 

The  age  of  the  Chitistone  limestone  was  long  in  doubt  but  is  now 
known  to  be  Upper  Triassic.  This  age  determination  is  based  on 
fossil  collections  made  in  1907  at  a number  of  localities  along  the 
limestone  area  from  Kotsina  River  to  the  Chitistone  and  on  larger 
collections  made  in  the  Nizina ‘district  in  1909.  All  the  collections 
were  submitted  to  T.  W.  Stanton  for  determination  and  the  forms 
present  are  contained  in  the  following  lists.  These  lists  include, 


24 


THE  NTZTNA  DISTRICT,  ALASKA. 


however,  only  the  species  collected  within  the  area  of  the  Nizina 
special  map.  The  numbers  given  the  specimens  are  the  catalogue 
numbers  in  the  National  Museum.  Concerning  the  collection  of  1907 
Dr.  Stanton  says  in  part : 

The  collection  is  small  and  fragmentary,  blit  it  has  proved  sufficient  to  show 
quite  conclusively  that  the  beds  in  question  are  of  Triassic  age.  The  am- 
monites, especially,  are  all  characteristic  Triassic  types,  and  the  few  brachiopods 
obtained  are  also  Mesozoic.  There  is  no  indication  of  Paleozoic  fossils  in  any 
part  of  the  section  represented.  * * * 

The  following  lists  give  the  form  recognized  from  each  locality.  In  most 
cases  specific  identifications  have  not  been  possible,  but  this  does  not  lessen  the 
accuracy  of  the  age  determination : 

Bonanza  mine  and  Bonanza  Creek : 

4808;  Nos.  9,  14  to  19,  21,  22— 

Undetermined  corals. 

Terebratula  sp. 

Spiriferina  sp. 

Hinnites?  sp. 

Pseudomonotis  subcircularis  (Gabb)? 

Jumbo  Creek,  near  the  Bonanza  mine: 

4809;  Nos.  10  to  13,  20— 

Pentacrinus  sp. 

Terebratula  sp. 

Avicula?  sp. 

Arcestes?  sp. 

The  last  two  named  are  certainly  Triassic  types  of  ammonites  and 
probably  belong  to  the  genera  to  which  they  are  provisionally  assigned. 
South  side  of  Chitistone  River : 

4810  : Nos.  23,  24— 

Spiriferina  ? sp. 

Halobia  sp. 

Arcestes?  sp. 

Tropites?  sp. 

The  last  two  are  Triassic  ammonites  provisionally  identified  from 
imperfect  specimens. 

The  list  of  fossils  collected  in  1909  is  here  arranged  by  localities. 
Dr.  Stanton  says  of  them : 

The  fossils  from  the  Chitistone  confirm  the  recent  determinations  of  that  hori- 
zon and  definitely  prove  that  it  is  of  Triassic  age. 

Jumbo  Creek : 

6300- 

Base  of  Chitistone  limestone  corals?  Too  obscure  for  identification. 
McCarthy  Creek : 

6330— 

Terebratula  sp.  Probably  Triassic. 

Nikolai  Creek : 

6303— 

Halobia  sp. ; related  to  H.  superba  Mojsisovics. 

Undetermined  Pelecypod. 

6306— 

Juvavites?  sp. 

Arcestes  sp. 


SEDIMENTARY  ROCKS. 


25 


Nikolai  Creek — Continued. 

6312— 

Pseudomonotis  subcircularis  (Gabb). 

Arcestes  sp. 

Juvavites?  2 sp. 

Orthoceras  sp. 

Cbitistone  River : 

6319— 

Tropites  sp. 

(Lower  part  of  Cbitistone  limestone.) 

6320— 

Halobia  superba. 

Arcestes. 

6333— 

Halobia  superba  Mojsisovics? 

Arcestes  sp. 

Copper  Creek : 

6321— 

Halobia  superba  Mojsisovics? 

When  Schrader  and  Spencer  studied  the  geology  of  the  Chitina 
Valley  in  1900  they  found  no  fossils  in  the  Chitistone  limestone  and 
were  unable  to  give  conclusive  evidence  concerning  the  age  of  the 
limestone.  They,  however,  correlated  it  with  the  massive  Carbonif- 
erous limestone  at  the  head  of  White  River,  first  described  by  Hayes® 
and  later  by  Brooks.* * 6 

This  limestone  is  exposed  on  the  north  side  of  Skolai  Creek,  one 
of  the  eastern  tributaries  of  Nizina  River,  and  is  conspicuous  in 
Skolai  Pass,  between  the  heads  of  Skolai  Creek  and  White  River. 
The  correlation  of  limestones  so  similar  in  appearance  and  so  near 
to  each  other  seemed  to  have  much  in  its  favor,  but  better  oppor- 
tunities for  study  have  proved  it  to  be  incorrect. 

Although  the  Chitistone  limestone  can  not  be  correlated  with  the 
limestone  on  White  River,  it  is  known  that  limestone  similar  in 
appearance  and  of  the  same  age  as  the  Chitistone  limestone  is  present 
on  the  north  side  of  the  Wrangell  Mountains,  in  the  depression  be- 
tween them  and  the  Nutzotin  Mountains.  There  is,  however,  no 
such  development  of  Triassic  limestone  there  as  is  seen  in  the  Chitina 
Valley,  and  the  known  exposures  are  confined  to  one  small  area. 

A table  of  correlations  for  the  Mesozoic  sedimentary  rocks  of 
Alaska  is  here  given,  from  which  it  appears  that  Triassic  rocks,  so 
far  as  they  are  known  at  present,  are  confined  to  the  region  south 
of  the  Alaska  Range.  Aside  from  the  Chitina  region,  Triassic  rocks 
probably  have  their  greatest  development  in  the  Cook  Inlet  region, 
wThere  they  occur  principally  in  the  form  of  cherts  with  a small 
proportion  of  shale  and  limestone  beds. 

° Hayes,  C.  Willard,  An  expedition  through  the  Yukon  district : Nat.  Geog.  Mag.,  vol.  4, 

1892,  p.  140. 

6 Brooks,  Alfred  H.,  A reconnaissance  from  Pyramid  Harbor  to  Eagle  City,  Alaska: 
Twenty-first  Ann.  Kept.  U.  S.  Geol.  Survey,  pt.  2,  1900,  p.  359. 


Correlation  of  the  Mesozoic  sedimentary  rocks  of  Alaska. 


26 


THE  NIZINA  DISTRICT,  ALASKA. 


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28 


THE  NTZTNA  DISTRICT,  ALASKA. 


McCarthy  shale. 

CHARACTER  OF  THE  FORMATION. 

The  term  McCarthy  Creek  shale  was  used  by  Rohn  to  designate  the 
black  shales  immediately  overlying  the  Chitistone  limestone,  and  the 
formation  was  described  by  him  as  “ a series  of  soft,  black,  highly 
fissile  shales  and  slates.”® 

The  formation  as  it  is  exposed  in  the  Nizina  district  is  essentially 
a shale  formation,  although  at  its  base  are  numerous  thin  limestone 
beds  forming  part  of  the  transition  zone  at  the  top  of  the  Chitistone 
limestone  or  the  base  of  the  shale.  Thin  beds  of  limestone  are  found 
interstratified  with  the  shales  wherever  they  are  exposed  within  the 
mapped  area,  but  are  not  abundant  and  form  only  a small  proportion 
of  the  whole.  The  top  of  the  McCarthy  shale  has  not  been  recog- 
nized. Bedding  is  easily  distinguished  in  most  places  either  by  the 
presence  of  the  thin  limestones  or  of  thin  limy  shale  beds  with 
surfaces  highly  colored  by  weathering.  Some  of  the  smooth  bare 
hilltops  about  the  eastern  tributaries  of  East  Fork  are  marked  with 
exceedingly  intricate  patterns  produced  by  the  colored  beds,  for  the 
McCarthy  shale  is  found  to  be  intensely  folded  wherever  it  has  been 
examined,  and  if  the  folds  are  cut  by  planes  or  curved  surfaces 
making  slight  angles  with  their  axes  the  patterns  appear. 

The  folding  in  the  McCarthy  shale  strongly  contrasts  with  both 
that  of  the  Chitistone  limestone  and  that  of  the  Ivennicott  formation. 
Pronounced  folding  took  place  in  the  upper  thin-bedded  part  of  the 
limestone  in  a few  localities.  It  begins  to  be  conspicuous  in  the 
transition  beds  at  the  base  of  the  shale  (see  PI.  IV,  B , p.  18)  but 
was  never  found  in  the  massive  beds  at  the  base  of  the  limestone. 
The  limestone  beds  were  more  able  than  the  shale  to  withstand  the 
pressure  that  tended  to  deform  them,  and  that  ability  increased  as  the 
thickness  of  the  beds  increased.  Another  factor  of  strength  lay  in 
the  massive  flows  of  the  Nikolai  greenstone,  which  lent  its  support 
to  the  heavy  beds  of  the  limestone  in  resisting  deformation. 

DISTRIBUTION. 

The  principal  area  of  McCarthy  shale  represented  on  the  geologic 
map  (PI.  Ill,  in  pocket)  lies  between  McCarthy  Creek  and  Nizina 
River,  at  the  north  edge  of  the  sheet.  This,  according  to  Rohn,  is 
the  south  edge  of  a succession  of  shales  extending  north  in  the 
McCarthy  Creek  valley  for  a distance  of  G or  8 miles  and  consti- 
tuting the  type  locality  for  the  formation.  This  is  not  only  the 
largest  area  of  the  shales  examined  but  it  also  shows  a greater  thick- 
ness than  any  other  area,  for  it  suffered  less  from  erosion  before  the 
Ivennicott  formation  was  deposited. 

a Rohn,  Oscar,  A reconnaissance  of  the  Chitina  River  and  the  Skolai  Mountains,  Alaska  : 
Twenty-first  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  2,  1900,  p.  426. 


SEDIMENTARY  ROCKS. 


29 


The  McCarthy  shale  and  the  shale-limestone  transition  zone  below 
it  form  the  base  of  the  mountains  south  of  Copper  Creek.  The  for- 
mation is  separated  from  the  overlying  Kennicott  formation  by  a 
distinct  unconformity,  but  the  black  shales  of  the  two  formations 
are  so  similar  in  appearance  that  they  were  not  distinguished  until 
the  detailed  work  of  1909  was  undertaken.  Only  the  base  of  the 
McCarthy  shale  is  exposed  on  Copper  Creek.  The  upper  part  was 
removed  by  erosion  before  deposition  of  the  Kennicott  began.  A 
smaller  area  of  the  Triassic  shale  forms  the  mountain  top  north  of 
Texas  Creek,  and  the  formation  is  present  in  other  places  overlying 
the  limestone  north  of  Dan  Creek  but  does  not  fall  within  the 
boundaries  of  the  mapped  area. 

THICKNESS. 

Accurate  measurements  of  the  thickness  of  the  McCarthy  shale 
were  not  obtained,  because  it  is  probable  that  only  a part  of  the  total 
thickness  is  exposed  within  the  mapped  area.  It  is  possible,  more- 
over, that  the  complete  original  section  is*  no  longer  represented  in 
this  district,  for  a long  erosion  interval  intervened  between  the  depo- 
sition of  the  Triassic  shales  and  the  Jurassic  shales.  During  this 
interval  much  of  the  Triassic  sedimentary  formations  and  of  the 
Nikolai  greenstone  was  removed.  Another  factor  of  uncertainty 
besides  the  amount  of  the  shales  that  have  been  removed  by  erosion 
is  the  thickening  and  reduplication  of  beds  that  arise  from  folding 
and  faulting.  It  is  probable,  however,  that  the  McCarthy  shale  has 
a thickness  nearly  as  great  as  the  Chitistone  limestone ; possibly  it  is 
greater. 

A thickness  of  about  1,500  feet  of  Triassic  shale  overlies  the  lime- 
stone on  the  west  side  of  Nizina  River.  The  shales  near  the  center 
of  the  broad  syncline  in  this  locality  have  a horizontal  position  and 
are  probably  less  distorted  by  folding  than  they  are  to  the  north- 
west. This  measurement  is  considered  the  minimum  and  probably 
much  less  than  the  true  thickness,  for  some  of  the  shale  has  certainly 
been  removed  by  erosion. 

The  mountains  about  the  head  of  the  East  Fork  of  McCarthy  Creek 
are  made  up  of  the  black  Triassic  shales.  They  reach  an  altitude  of 
6,960  feet  above  sea  level  or  3,000  feet  above  the  limestone  shale 
boundary  at  the  creek  on  the  southwest.  The  shales  are  much  folded 
about  the  upper  part  of  the  East  Fork  valley,  and  measurements  are 
consequently  uncertain,  but  it  is  probable  that  the  thickness  of  the 
formation  is  at  least  2,500  feet  in  this  vicinity.  ^No  measurements  of 
value  were  obtained  in  the  Copper  Creek  section,  for,  as  previously 
stated,  only  a part  of  the  formation  is  present  there. 

It  is  evident  from  what  has  been  said  that  the  total  thickness  of 
Triassic  sediments  in  the  Nizina  district  is  great  and  that  it  is  prob- 


30  THE  NIZINA  DISTRICT,  ALASKA. 

ably  not  less  than  6,000  feet.  One-half  of  this  figure  represents  a 
limestone  whose  thickness  can  be  stated  with  a considerable  degree  of 
accuracy;  the  remainder  represents  a great  shale  formation  whose 
thickness  is  stated  only  approximately. 

AGE. 

The  McCarthy  shale  is  of  Upper  Triassic  age.  Some  of  the  beds 
are  abundantly  fossiliferous,  especially  those  near  the  base  of  the 
formation  and  in  the  transition  zone  below,  and  fossils  can  usually 
be  found  in  the  higher  parts  of  the  formation  if  search  is  made  for 
them.  Shells  of  Pseudomonotis  subcircularis  (Gabb)  are  so  plentiful 
in  some  of  the  shale  beds  between  the  thin  limestones  that  the  rock 
can  not  be  broken  without  showing  them;  they  appear,  however,  to 
be  almost  the  only  forms  represented. 

A list  of  fossil  localities  follows;  the  determinations  are  by  T.  W. 
Stanton. 

McCarthy  Creek : * 

6314— 

Pseudomonotis  subcircularis  (Gabb). 

Nikolai  Creek: 

6311- 

Two  or  more  undetermined  ammonite  genera  represented  by  frag- 
mentary specimens. 

Dan  Creek : 

6317— 

Pseudomonotis  subcircularis  (Gabb). 

Copper  Creek  (two  localities)  : 

6323 — 

Pseudomonotis  subcircularis  (Gabb). 

6335— 

Pseudomonotis  subcircularis  (Gabb). 

Areas  of  Triassic  shale  are  scattered  along  the  south  slope  of  the 
Wrangell  Mountains  as  far  west  as  the  Kuskulana  and  probably  as 
far  as  the  Kotsina  also,  but  in  the  earlier  work  in  this  region  the 
Triassic  shales  and  the  black  Jurassic  shales  were  not  separated 
because  the  presence  of  an  immense  thickness  of  Jurassic  shales  in 
this  valley  was  not  known  at  that  time.  It  is  now  certain  that  a 
considerable  part  of  the  shale  areas  of  Chitina  Valley  formerly  con- 
sidered to  be  Triassic  are  in  reality  of  Jurassic  age. 

No  Triassic  shale  corresponding  in  thickness  or  other  characters 
to  the  McCarthy  shale  is  known  in  Alaska.  Other  regions  of  Triassic 
sediments  of  similar  age  have  been  pointed  out  (see  correlation  table, 
pp.  26-27),  but  the  conditions  under  which  they  were  deposited  were 
different  from  those  in  the  Nizina  district,  and  although  they  may 
be  in  part  contemporaneous  the  resulting  formations  are  distinct. 


SEDIMENTARY  ROCKS. 


31 


JURASSIC  SYSTEM. 

KENNICOTT  FORMATION. 

CHARACTER  OF  THE  FORMATION. 

The  name  Kennicott  was  adopted  by  Rohn  to  designate  the  con- 
glomerate and  sandstone  succession  which  he  found  resting  uncon- 
formably  on  the  Triassic  shales  of  McCarthy  Creek  and  correlated 
on  fossil  evidence  with  the  light-colored  arkoses,  shales,  and  lime- 
stones between  Lachina  River  and  Kennicott  Glacier.  Rohn  did  not 
recognize  the  black  shale  south  of  Nikolai  Creek  as  part  of  his  Kenni- 
cott formation,  but  within  the  district  under 
consideration  the  black  shale  is  far  more 
important  in  amount  than  the  basal  con- 
glomerate and  sandstone  members. 

The  Kennicott  formation  as  the  term  is 
here  used  consists  largely  of  black  shale,  but 
it  includes  conglomerate,  grit,  sandstone,  and 
impure  limestone  members  and  is  intruded 
by  great  masses  of  light-colored  porphyritic 
rock.  It  is  the  youngest  of  the  consolidated  « 
sedimentary  deposits  represented  on  the  geo-  § 
logic  map  (PI.  Ill,  in  pocket)  and  is  more 
widely  distributed  within  the  mapped  area 
than  any  of  the  formations  previously  de- 
scribed. One  of  the  characteristics  of  the 
Kennicott  is  its  variation  in  appearance 
and  composition  at  different  localities.  This 
statement  is  more  applicable  to  its  basal  than 
to  its  upper  part  and  refers  to  features  £ 
that  resulted  from  changing  shore  conditions  | 
of  sedimentation.  These  differences  will  be  w 
brought  out  by  a description  of  the  Jurassic 
rocks  northwest  of  Nizina  River,  where  the 
basal  part  is  better  represented,  and  south-  Fl 
east  of  Nizina  River,  where  the  middle  and 
upper  parts  are  better  represented. 

The  Kennicott  formation  where  it  is  exposed  about  the  head  of 
Nikolai  Creek  may  be  subdivided  into  three  members  as  follows: 
A basal  member  made  up  of  conglomerate  and  sandstone ; a second 
member  consisting  chiefly  of  light-gray,  yellow-weathering  shale; 
and  an  upper  member  of  dark-gray  or  black  shale  interstratified 
with  occasional  beds  of  impure  limestone  or  hard  calcareous  shale 
(fig.  2).  The  basal  member  shows  notable  differences  in  lithologic 
character  and  thickness  as  it  is  followed  from  one  outcrop  to  another. 


Black  shale  with  hard 
calcareous  beds ; fos- 
sils. 


Gray,  yellow-weather- 
ing shales;  fossils. 


Y ellow-w  eathering 
sandy  shales. 


Yellow-w  eathering 
sandstones;  fossils. 


Conglomerate  (locally 
with  large  blocks 
and  bowlders)  grad- 
ing upward  into  fine 
grit.  Some  beds  with 
an  abundance  of 
broken  shells. 

Unconformity. 

Limestone  and  green- 
stone. 


gure  2. — Columnar  section 
of  the  basal  part  of  the 
Kennicott  formation  ex- 
posed on  Nikolai  Creek. 


32 


THE  NIZINA  DISTRICT,  ALASKA. 


These  differences,  except  in  thickness,  are  dependent  in  large  measure 
on  the  kind  of  rock  immediately  underlying  the  Kennicott.  In 
nearly  all  places  the  lowest  beds  of  the  formation  consist  of  con- 
glomerate, but  this  conglomerate  presents  a different  appearance  in 
almost  every  exposure,  for  there  is  nearly  every  gradation  between 
an  even-grained  grit  who§e  well-worn  pebbles  are  of  uniform  size 
and  no  larger  than  grains  of  wheat  to  a coarse  agglomerate  with 
blocks  and  bowlders  up  to  8 or  10  feet  in  diameter  (PI.  YI,  A). 
Such  coarse  material  has  probably  traveled  but  a short  distance 
from  its  source  and  may  represent  a shore-line  cliff.  It  is  not  a 
constant  feature  of  the  basal  Kennicott  and  its  exposures  are  not 
extensive,  for  the  very  large  bowlders  are  found  in  only  a few 
localities.  In  many  places  it  was  noticed  that  most  of  the  pebbles 
in  the  conglomerate  are  of  the  same  material  as  the.  older  beds  on 
which  the  conglomerate  rests — that  is,  where  conglomerate  overlies 
greenstone  most  of  the  pebbles  are  greenstone  and  where  it  rests  on 
the  Triassic  shale  most  of  the  pebbles  are  shale.  Limestone  pebbles 
are  not  so  numerous  as  pebbles  of  greenstone  and  shale,  yet  con- 
glomerate of  this  formation  containing  a large  proportion  of  rounded 
limestone  fragments  is  found  in  other  parts  of  the  Chitina  Valley. 
Some  of  the  conglomerate  contains  a considerable  number  of  diorite 
and  porphyry  pebbles,  but  it  was  not  found  in  place  in  the  vicinity 
of  Nikolai  Creek,  where  the  basal  conglomerate  of  the  Kennicott 
is  best  developed  wdthin.  the  area  mapped.  Nearly  all  of  the  frag- 
ments are  well  rounded  and  waterworn,  and  it  is  only  in  the  very 
coarse  conglomerate  that  angular  outlines  are  noticeable.  Even  in 
such  places  the  edges  and  corners  of  the  blocks  are  usually  worn 
away. 

The  filling  between  pebbles  is  finely  ground  material  from  the  same 
source  as  the  pebbles  and  is  for  the  most  part  a greenish  sandstone  or 
graywacke.  The  average  size  of  fragments  composing  the  basal  mem- 
ber of  the  formation  decreases  rapidly  as  distance  from  the  base  in- 
creases, until  the  conglomerate  gives  way  to  sandstone.  In  most  local- 
ities about  Nikolai  Creek  where  exposures  occur  it  is  found  that  the  up- 
per half  or  three- fourths  of  the  basal  member  consists  of  fine  greenish 
sandstone  or  graywacke  containing  little  quartz  and  seemingly  derived 
largely  from  the  Triassic  shale  and  the  greenstone.  This  upper  part 
shows  far  less  variation  in  character  than  the  conglomerate,  although 
in  the  base  thin  beds  of  graywacke  alternate  with  thin  beds  of  con- 
glomerate. There  are  places  where  the  fine  conglomerate  and  gra}T- 
wacke  contain  considerable  lime  and  become  practically  an  impure 
limestone,  but  such  beds  are  not  persistent.  Some  of  them  consist 
in  part  of  broken  shells,  yet  it  is  difficult  to  find  determinable  fossils 
among  them  and  still  more  difficult  to  secure  the  fossils  when  found, 
since  they  are  in  most  cases  partly  decomposed  and  fragile. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  VI 


A.  BOWLDERS  IN  CONGLOMERATE  AT  BASE  OF  KENNICOTT  FORMATION  ON  SOUTH 
BRANCH  OF  NIKOLAI  CREEK. 

See  page  32. 


B.  SANDSTONE  OF  KENNICOTT  FORMATION  ON  RIDGE  SOUTH  OF  NIKOLAI  MINE. 

See  page  33. 


SEDIMENTARY  ROCKS. 


33 

This  lowest  conglomerate-sandstone  member  of  the  Kennicott  for- 
mation on  Nikolai  Creek  has  a thickness  ranging  from  25  to  125 
feet,  the  greater  part  of  which  is  graywacke,  the  remainder  con- 
glomerate or  grit.  In  a few  places  the  basal  member  appears  to  be 
entirely  absent,  although  because  of  faulting  and  talus  slopes  its 
seeming  absence  may  be  explained  in  other  ways.  Furthermore,  its 
persistence  as  a whole  in  many  other  places  in  spite  of  rapid  changes 
in  character  and  of  variation  in  thickness  makes  it  probable  that  if 
it  is  not  seen  in  a particular  locality  the  failure  to  find  it  is  due  to  one 
of  the  causes  mentioned. 

The  middle  member  of  the  formation  on  Nikolai  Creek  shows  far 
less  variation  in  character  than  the  lower  one,  but  it  does  not  ap- 
pear so  conspicuously  in  other  parts  of  the  Nizina  region.  It  con- 
sists of  shale  and  shaly  sandstone,  but  shale  predominates.  The 
sandy  phases  are  more  or  less  local,  and  the  best  exposures  are  on 
the  ridge  south  of  Nikolai  mine  (PL  VI,  B).  A freshly  broken 
surface  of  the  shale  showTs  a fine-grained  rock  of  light  color,  but 
both  shale  and  sandstone  weather  a bright  yellow  that  makes  them 
conspicuous  wherever  they  are  exposed.  Both  shale  and  sandstone 
break  down  into  thin  fragments  under  the  influence  of  the  weather, 
and  the  debris  from  their  ledges  give  rise  to  prominent  talus  slopes. 
Occasionally  fossils  are  found  in  the  sandstone,  and  rarely  a shell  is 
seen  in  the  shale,  but  fossils  are  not  abundant  and  it  requires  some 
search  to  find  any  of  value.  The  thickness  of  the  yellow- weathering 
shales  is  as  great  as  500  feet  in  the  mountain  between  Nikolai  Creek 
and  the  East  Fork  of  McCarthy  Creek.  At  the  head  of  Nikolai  Creek 
375  feet  of  yellow- weathering  shale  overlies  the  conglomerate,  but 
some  of  the  shale  has  been  eroded  away. 

The  highest  member  of  the  Kennicott  in  the  Nikolai  Creek  vicinity 
consists  of  black  shale,  with  interstratified  hard,  impure  limestone 
and  calcareous  shale  beds  ranging  in  thickness  from  1 inch  to  2 feet. 
The  hard  beds  form  only  a small  proportion  of  the  total  thickness, 
probably  less  than  one-tenth,  but  although  jointed  and  broken  they 
stand  out  in  relief  from  the  softer,  crumbling  black  shales  and  form 
a conspicuous  part  of  the  whole.  This  black  shale  resembles  closely 
the  black  shales  of  the  Triassic.  The  hard  beds  assume  a rusty- 
yellowish  color  on  weathering,  just  as  in  the  Triassic  shales,  and 
there  seems  to  be  no  way,  except  by  their  stratigraphic  position  and 
their  fossils,  to  distinguish  them  from  the  older  shales.  Fossils  are 
fairly  plentiful  in  some  beds  of  this  member,  especially  those  in  the 
hard  beds,  and  are  in  a better  state  of  preservation  than  those  found 
lower  in  the  formation. 

From  125  to  150  feet  of  these  shales  are  exposed  north  of  Nikolai 
Creek,  but  the  figures  take  no  account  of  what  has  been  removed  by 
erosion  or  what  has  been  caught  up  into  the  intruded  porphyry. 

70648°— Bull.  448—11 -3 


34 


THE  NIZINA  DISTRICT,  ALASKA. 


Locally  erosion  has  destroyed  the  upper  member,  leaving  the  basal 
and  middle  members.  In  some  localities  both  the  middle  and  the 
upper  members  have  been  removed,  and  without  doubt  the  Kenni- 
cott  was  once  present  in  large  areas  where  no  trace  of  it  is  now  found. 

The  section  of  the  Kennicott  formation  exposed  on  Dan  Creek  is 
many  times  thicker  than  the  section  that  has  been  described.  The 
Nikolai  section  represents  a phase  of  the  basal  Kennicott  that  is 
thought  to  correspond  more  fully  with  the  Kennicott  observed  west 
of  Kennicott  Glacier  and  still  farther  west  in  the  Chitina  Valley 
than  does  the  Dan  Creek  section.  An  excellent  exposure  of  the  base 
of  the  Kennicott  formation  was  found  on  Eagle  Creek,  in  the  Copper 
Creek  valley.  All  the  upper  part  of  the  long  ridge  separating 
Eagle  Creek  from  Copper  Creek  is  made  up  of  lower  Kennicott  beds. 
They  rest  on  the  edges  of  thin  limestone  and  shale  beds  that  belong 
to  the  transition  zone  between  Chitistone  limestone  and  McCarthy 
shale.  The  limestone  and  shale  beds  have  a dip  about  20°  greater 
than  the  overlying  Kennicott,  and  the  unconformity  is  shown  in 
diagrammatic  clearness.  The  basal  beds  of  the  Kennicott  at  this 
place  consist  of  from  150  to  200  feet  of  fine  conglomerate  or  grit 
overlain  by  sandstone.  Black  shale  overlies  the  sandstone  and  forms 
the  top  of  the  ridge  extending  southeast  to  the  main  mountain  mass. 
This  basal  grit  was  traced  northwest  in  Copper  Creek  valley  to 
the  vicinity  of  the  limestone  area  north  of  Idaho  Gulch.  It  may 
be  regarded  as  a constant  feature  of  the  Kennicott  in  the  Nizina 
district.  In  most  places  it  is  somewhat  fossiliferous.  Pyramid 
Peak,  at  the  head  of  Copper  Creek,  appears  to  be  made  up  entirely 
of  rocks  belonging  to  the  Kennicott  formation.  The  lower  part  is 
black  shale,  but  the  top  shows  bedding  lines  that  are  thought  to  rep- 
resent sandstones  and  impure  limestones.  Sandy  shales  and  hard 
sandstones  are  interstratified  wfith  the  black  shales  on  Rex  Creek, 
and  the  tops  of  the  mountains  between  Rex  Creek  and  White  Creek 
contain  a large  amount  of  gray  sandstone  and  impure  limestone. 
Beds  of  brown-weathering  nodular  limestone  in  the  shales  high  up 
on  the  slopes  of  these  mountains  contain  ammonite  shells  15  or  18 
inches  across.  These  mountains  appear  to  be  at  the  axis  of  a broad 
shallow  syncline  and  give  good  sections  of  the  formation. 

A feature  of  geologic  interest  is  presented  by  the  sandstone  dikes 
that  cut  the  black  shales  east  of  Rex  Creek.  These  dikes  range  in 
thickness  from  a fraction  of  an  inch  to  5 or  6 inches  and  cut  the  shales 
just  as  an  igneous  dike  would.  They  are  composed  of  angular  frag- 
ments of  quartz,  feldspar,  biotite,  calcite,  and  pyrite  mingled  with 
fragments  of  shale.  They  are  composed  of  the  same  material  as  some 
of  the  associated  sandstone  beds  and  are  numerous  in  places. 

Bedding  in  the  black  shales  of  Blei  Gulch,  on  the  south  side  of 
Chititu  Creek,  is  shown  by  lines  of  small  limestone  concretions  and 


SEDIMENTARY  ROCKS. 


35 


thin  discontinuous  calcareous  beds.  More  than  4,500  feet  of  black 
shale  dipping  low  to  the  southwest  is  exposed  in  Blei  Gulch.  Young 
Creek,  south  of  Chititu  Creek,  flows  in  a shallow  canyon  whose  walls 
are  composed  of  black  shale  of  the  Kennicott  formation.  This  shale 
forms  the  lower  slopes  of  the  ridge  south  of  Young  Creek,  and  it  is 
probable  that  Kennicott  sediments  make  up  most  of  the  ridge.  The 
ridge  was  not  examined  in  detail  owing  to  lack  of  time,  but  a section 
up  the  first  southern  tributary  of  Young  Creek  east  of  Calamity  Gulch 
shows  rocks  of  the  Kennicott  formation.  The  section  extends  up  the, 
east  branch  of  this  creek.  For  a distance  of  nearly  three-fourths  of 
a mile  from  its  mouth  the  creek  flows  over  black  shales  with  occa- 
sional limestone  beds,  all  dipping  southwest  at  angles  of  30°  or  less. 
Thence  for  nearly  a fourth  of  a mile  are  rocks  that  have  been  crumpled 
and  much  faulted.  They  consist  of  shales  with  interbedded  cal- 
careous shales  and  limestone,  from  which  fossils  were  collected.  In 
many  places  the  strata  of  this  disturbed  zone  stand  on  edge,  and  it 
is  evident  that  displacements  of  importance  have  taken  place.  A 
peculiar  feature  of  this  locality  is  seen  in  the  limestone  nodules,  which 
occur  in  beds  and  reach  diameters  of  2 or  3 feet.  They  consist  of 
bluish-gray  limestone  and  show  parallel  bedding  lines  crossing  them. 
They  were  seen  at  a number  of  places  on  Young  Creek.  South  of  this 
faulted  zone  the  creek  flows  for  another  three- fourths  of  a mile  over 
black  shales  and  thin  gray  and  brown  sandstones.  The  shale  pre- 
dominates but  the  sandstones  form  an  important  part  of  the  whole. 
The  dip  of  these  shales  and  sandstones  is  steeper  than  is  usual  in  the 
Kennicott  formation  of  the  Nizina  district,  ranging  from  30°  to  50°. 
A massive  conglomerate  succeeds  the  shale  and  limestone  on  the  south 
at  a point  1,500  feet  above  Young  Creek.  The  conglomerate  is 
several  hundred  feet  thick  and  is  made  up  of  well-rounded  pebbles 
loosely  cemented  together,  many  of  which  are  5 or  6 inches  in  diam- 
eter. It  appears  to  have  been  deposited  conformably  on  the  under- 
lying shale-sandstone  beds,  but  there  is  reason  to  believe  that  move- 
ment has  taken  place  along  the  contact  at  this  locality.  No  proof 
was  secured  to  show  that  this  great  conglomerate  does  not  mark  an 
unconformity  in  the  Kennicott  formation  or  between  the  Kennicott 
and  a succeeding  formation,  but  the- relation  appears  to  be  one  of 
conformity  in  other  places  west  of  this  creek  where  the  contact  was 
examined.  Flat-topped  or  mesa-like  hills  composed  of  conglomerate 
beds  dipping  low  to  the  south  are  scattered  along  the  top  of  this 
ridge  both  to  the  east  and  to  the  west  of  this  section.  According  to 
Schrader’s  field  notes  of  1900,  the  conglomerate  on  the  west  end  of 
the  ridge  south  of  Young  Creek  is  interstratified  with  a few  beds  of 
arkose  sandstone  and  probably  does  not  exceed  500  feet  in  thickness. 
It  contains  granite  bowlders  up  to  9 inches  in  diameter,  dark  lime- 
stone, flint,  quartz,  gray  slate  and  grit,  and  green  gneissic  rock,  but 


36 


THE  NIZINA  DISTRICT,  ALASKA. 


Schrader  did  not  find  any  pebbles  of  Nikolai  greenstone.  The  arkose 
or  sandstone  underlying  the  conglomerate  was  measured  by  Schrader 
in  a very  favorable  section,  where  the  dip  was  low  to  the  south-south- 
east, and  was  found  to  be  between  2,000  and  2,500  feet  in  thickness. 

There  is  no  reason  to  doubt  that  this  succession  of  shales,  lime- 
stones, sandstones,  and  conglomerate  found  in  the  ridge  south  of 
Young  Creek  corresponds  to  the  bedded  rocks  seen  in  the  high  moun- 
tains at  the  head  of  Copper,  Rex,  and  White  creeks.  It  therefore 
represents  the  upper  part  of  the  Kennicott  formation  as  it  is  known 
at  present. 

The  unconformable  relation  of  the  Kennicott  formation  to  the 
older  sedimentary  rocks  and  the  Nikolai  greenstone  is  plainly  seen 
in  both  the  localities  whose  sections  have  been  described  and  is  shown 
in  the  view  (Pl.  VII,  A and  B)  taken  at  the  head  of  Nikolai  Creek. 
Kennicott  sediments  there  rest  on  the  upturned  and  truncated  beds 
of  the  Nikolai  greenstone,  the  Chitistone  limestone,  and  the  Mc- 
Carthy shale.  The  dip  of  the  younger  beds  is  low  in  most  places, 
ranging  from  10°  to  20°  W.  or  SW.  On  the  other  hand,  the  dip 
of  the  underlying  sediments  and  the  lava  flows  (Nikolai  greenstone) 
are  considerably  greater  and  in  a different  direction,  averaging  about 
30°  or  35°  NE. 

One  feature  of  the  Jurassic  sediments  that  is  more  noticeable  on 
White  and  Young  creeks  than  in  other  parts  of  the  district  is  the 
rapidity  with  which  they  break  down  under  the  action  of  weathering. 
Such  topographic  forms  as  Blei  Gulch  and  the  gulches  tributary 
to  Young  Creek  are  due  to  this  cause.  Blei  Gulch  in  particular 
shows  how  readily  the  shales  are  attacked  and  how  little  they  are 
able  to  resist  the  attacks  as  compared  with  the  greenstone  and  lime- 
stone. The  soft  shale  debris  accumulates  faster  than  the  water  can 
carry  it  away  and  the  mouth  of  the  gulch  is  choked  with  it. 

The  Kennicott  was  deposited  on  an  old  submerged  land  surface. 
In  a broad  way  this  surface  on  which  the  Kennicott  formation  of 
Nikolai  Creek  lies  was  flat,  but  it  is  readily  seen  on  examining  the 
contact  that  there  wrere  minor  irregularities  in  it  such  as  are  present 
in  any  level  country.  The  conglomerate  and  graywacke  beds  of  the 
basal  Kennicott  sag  down  into  hollows  of  the  underlying  surface, 
and  at  one  locality  pebbles  and  sand  were  seen  filling  old  cracks  in 
the  Chitistone  limestone. 

DISTRIBUTION. 

The  Kennicott  formation  occupies  probably  three-fourths  of  the 
total  area  represented  on  the  geologic  map  (PI.  Ill,  in  pocket),  for  if 
a line  be  drawn  from  the  mouth  of  National  Creek  to  Pyramid  Peak 
practically  all  of  the  consolidated  deposits  south  of  it  are  Kennicott. 
It  forms  the  high  angular  mountains  between  Dan  and  Chititu 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  VII 


B. 

UNCONFORMITY  BETWEEN  TRIASSIC  AND  JURASSIC  FORMATIONS  AT  HEAD  OF  NIKOLAI  CREEK. 

a,  Sandstone  and  shale  of  Kennicott  formation;  b,  Chitistone  limestone;  c,  Nikolai  greenstone.  The  two  views 
placed  side  by  side  would  form  a panorama.  See  page  36. 


SEDIMENTARY  ROCKS. 


37 


Conglomerate  with 
interbedded  sand 
stone. 


creeks  and  makes  up  the  principal  part  of  Porphyry  and  Sourdough 
peaks,  although  its  presence  is  so  obscured  by  porphyry  intrusions 
in  these  two  last-mentioned  mountains  that  its  amount  is  apt  to  be 
underestimated.  It  doubtless  underlies  also 
the  gravel  deposits  of  the  lowland  south  of 
Nizina  River. 

Without  question  Jurassic  sediments  are  far 
more  widespread  in  Chititu  Valley  than  was 
suspected  before  the  field  work  of  1909  was 
undertaken.  They  extend  eastward  beyond 
the  Nizina  district  into  the  upper  valley  of 
the  Chitina  and  westward  along  the  flanks  of 
the  Wrangell  Mountains,  where  it  is  certain 
that  they  have  not  been  fully  differentiated 
from  the  Triassic  shales,  just  as  was  true  in 
the  Nizina  district.  The  separation  of  Juras- 
sic from  Triassic  shales  will  require  more  de 


Black  shale  with  a 

few  limestone 

— ^ beds. 


tailed  field  work  than  has  yet  been  given  them. 

THICKNESS. 

No  such  favorable  section  was  found  for 
measuring  the  thickness  of  the  Kennicott  for- 
mation as  that  furnished  by  the  walls  of 
Nizina  River  for  measuring  the  Chitistone 
limestone,  and  the  figures  given  are  secured 
from  a study  of  a number  of  sections  at  differ- 
ent localities  (fig.  3).  The  total  thickness 
given  should  be  regarded  as  having  only 
approximate  accuracy. 

The  coarse  fragmental  beds,  including  con- 
glomerate and  grit  at  the  base  of  the  Kenni- 
cott, range  in  thickness  from  25  to  150  or  200 
feet.  An  intermediate  figure  of  100  to  150 
feet  is  believed  to  represent  a fair  estimate  for 
the  thickness  of  these  beds  throughout  the  dis- 
trict. It  seems  proper  to  include  the  yellow- 
weathering shales  and  sandstones  of  Nikolai 
Creek  with  the  black  shales,  since  they  are  a 
local  feature  and  contemporaneous  in  time  of 
deposition  with  the  lower  part  of  the  black 
shale  south  of  Nizina  River.  On  this  basis  the  black  shale  mem- 
ber at  the  heads  of  Copper  and  Rex  creeks  has  a minimum  thick- 
ness of  not  less  than  4,500  feet,  yet  the  black  shales  of  Williams 
Peak  south  of  Dan  Creek  suggest  a considerably  greater  thick- 
ness, possibly  as  much  as  6,000  feet.  This  measurement  includes 
all  beds  from  the  top  of  the  conglomerate  and  grit  to  the  begin- 


Interbedded  sand- 
stone and  shale. 


Yellow  -weathering 
shale  and  sand- 
stone; changes  to 
black  shale  in 
places. 

Conglomerate. 

Triassic  shale-lime- 
stone beds. 


Figure  3.  — Generalized 
columnar  section  of  the 
Jurassic  sediments  in 
the  Nizina  district. 


38 


THE  NIZINA  DISTRICT,  ALASKA. 


ning  of  the  interbedded  shale-sandstone  succession  that  forms  the 
tops  of  the  high  mountains  at  the  heads  of  Copper  and  Rex  creeks 
and  the  upper  part  of  the  ridge  south  of  Dan  Creek.  The  shale- 
sandstone  member  has  a thickness  of  about  2,500  feet.  If,  now, 
500  fee*,  representing  the  heavy  conglomerate  of  Young  Creek,  be 
added  to  the  measurements  already  given,  a minimum  thickness  of 
over  7,500  feet  is  obtained  for  the  Kennicott  formation  in  the  Nizina 
district. 

AGE  AND  CORRELATION. 


Fossils  have  been  collected  from  all  parts  of  the  Kennicott  forma- 
tion, but  unfortunately  the  stratigraphic  range  of  the  forms  is  so 
great  that  they  do  not  fix  its  age  definitely.  It  appears  most  prob- 
able that  the  Kennicott  formation  was  laid  down  in  Upper  Jurassic 
time,  but  there  is  a possibility  of  its  being  Lower  Cretaceous.  The 
probability  of  its  Jurassic  age  rests  in  considerable  measure  on  the 
presence  of  a species  of  Aucella  collected  first  by  Rohn  and  later  by 
Schrader  and  Spencer  and  identified  by  T.  W.  Stanton.  Schrader 
and  Spencer  collected  fossils  at  other  localities  as  well  as  in  the  Nizina 
district,  and  on  the  evidence  of  these  fossils  the  formation  was 
referred  to  u the  doubtful  series  lying  at  the  top  of  the  Jurassic  or  at 
the  base  of  the  Cretaceous.”" 

The  list  of  fossils  follows. 


Inoceramus  eximius  Eicliwald? 
Belemnites  sp. 

Halobia  occidentals  AVliiteaves? 
Rhynchonella  sp. 

Pecten  sp. 

Avion  la  sp. 


Aucella  pallasi  Keyserling? 
Lytoceras  sp. 

Hoplites  sp. 

Olcostephanus?  sp. 

Gryphaea  sp. 

Sagenopteris  sp. 


Concerning  Inoceramus  eximius  Dr.  Stanton  says : ° 

This  form  is  represented  by  a single  specimen  collected  on  Chitty  Creek. 
It  may  be  distinct  from  Eichwald’s  species  originally  described  from  Turkusitun 
Bay,  in  Cook  Inlet,  and  referred  by  him  to  the  Neocomian.  Eichwald  described 
three  other  species — /.  ambiguus , I.  porrectus,  and  I.  lucifer — all  belonging 
to  one  section  of  Inoceramus  from  the  same  horizon  in  Alaska.  The  present 
shell  does  not  agree  perfectly  with  any  of  the  figures,  but  it  is  most  nearly 
like  I.  eximius  and  probably  comes  from  the  same  formation.  Similar  forms 
occur  both  in  the  Jurassic  and  in  the  Cretaceous,  but  the  evidence  of  the  other 
fossils  from  this  part  of  Alaska  favors  the  reference  of  the  Kennicott  forma- 
tion to  the  Jurassic. 


° Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion  of 
the  Copper  River  district,  Alaska:  Special  publication  of  the  U.  S.  Geol.  Survey,  1901, 
p.  50. 


SEDIMENTARY  ROCKS. 


39 


Of  the  form  referred  with  a question  to  Halobia  Occident  alls  Dr. 
Stanton  says: 

The  specimens  agree  fairly  well  in  sculpture  and  general  appearance  with 
some  of  the  figures  of  Whiteaves’s  species  from  the  Liard  River  and  may  be 
identical  with  it.  They  are,  however,  somewhat  suggestive  of  Hinnites  linwnsis, 
from  the  Jurassic(?)  of  Siberia. 

Sagenopteris  is  a genus  which  occurs  both  in  the  Jurassic  and  in  the  Cre- 
taceous, but  the  species  is  thought  by  Prof.  Ward,  to  whom  it  was  shown,  to  be 
near  a species  occurring  in  the  Jurassic  of  the  Pacific  coast. 

Concerning  the  general  relations  of  the  fossils  from  the  Kennicott 
formation  Dr.  Stanton  observes: 

These  fossils  are  all  either  Upper  Jurassic  or  Cretaceous,  with  a suggestion 
of  a somewhat  younger  age  for  a few  localities.  In  the  present  state  of  knowl- 
edge and  with  these  small  collections  it  is  not  practicable  to  determine  whether 
they  represent  one  horizon  or  several.  In  my  opinion,  they  probably  all  belong 
to  the  Upper  Jurassic,  though  subsequent  work  may  show  the  contrary.  The 
question  is  connected  with  the  still  unsolved  problem  of  the  exact  boundary 
between  the  Jurassic  and  the  Cretaceous  in  the  Aucella- bearing  beds  of  Russia, 
Siberia,  and  the  Pacific  coast  region  of  North  America.  The  Aucella  occurring 
in  the  Copper  River  district  appears  to  be  referable  to  a Russian  Jurassic 
species,  but  it  is  also  quite  similar  to  the  Cretaceous  form  in  the  lower  Knox- 
ville beds  of  California.  The  few  other  forms  are  mostly  undescribed  species 
of  types  that  occur  both  in  the  Jurassic  and  in  the  Lower  Cretaceous. 

A single  fossil  collected  on  Chititu  Creek  in  1907  was  referred  to 
Dr.  Stanton  and  described  by  him  thus: 

Chititu  Creek : 

4S11 ; No.  26— 

Perisphinctes,  sp.  This  ammonite  is  not  a typical  Perisphinctes,  but  it 
is  probably  of  Jurassic  age,  certainly  not  older  than  Jurassic. 

The  much  larger  collection  made  in  1909  was  also  referred  to  Dr. 
Stanton,  who  says  of  them : “ The  fossils  from  the  Kennicott  indi- 
cate that  one  fauna  ranges  throughout  the  formation  and  that  its 
age  is  most  probably  Jurassic,  though  the  types  represented  in  the 
collection  are  not  as  definite  as  could  be  wished  for  determining 
between  Jurassic  and  Cretaceous.  The  entire  absence  of  Aucella  is 
noteworthy  in  view  of  the  fact  that  that  genus  has  previously  been 
reported  from  the  formation.”  The  list  of  fossils  arranged  by  lo- 
calities and  with  the  catalogue  numbers  of  the  National  Museum 
follows. 

McCarthy  Creek : 

6301— 

Inoceramus  sp. 

6313— 

Lytoceras  sp. 

Phylloceras  sp. 

Base  of  Kennicott. 


40 


THE  NIZINA  DISTRICT,  ALASKA, 


Nikolai  Creek : 

0302— 

Inoceramus  sp. 

Base  of  Kennicott. 

6304— 

Rhynchonella  sp. 

Pecten  sp. 

Base  of  Kennicott. 

6305— 

Rhynchonella  sp. 

Terebratella  ? sp. 

Exogyra  sp. 

Pecten  sp. 

Collected  near  6304. 

6307— 

Phylloceras  sp. 

6308— 

Inoceramus  sp. 

Lower  part  of  Kennicott  formation. 

6309— 

Rhynclionella  sp. 

Inoceramus  sp. 

6310— 

Rhynchonella  sp. 

Terebratella?  sp. 

Base  of  Kennicott  formation. 

6331— 

Rhynchonella  sp. 

Terebratella?  sp. 

Ostrea  sp. 

Rear  base  of  Kennicott  formation. 
Sourdough  Hill : 

6315— 

Inoceramus  sp. 

Dan  Creek: 

6316— 

Inoceramus  sp. 

6318- 

Bowlder  in  conglomerate  of  Kennicott  formation. 
Halobia  superba  Mojsisovics? 

. Copper  Creek : 

0322— 

Rhynchonella  sp. 

Undetermined  small  Telecypoda. 

Natica  sp. 

Undetermined  ammonite. 

Base  of  Kennicott  formation. 

Texas  Creek : 

6334— 

Phylloceras?  sp. 

Rex  Creek : 

6324- 

Irregular  echinoid,  crushed  specimens. 

Pecten  sp. 


SEDIMENTARY  ROCKS. 


41 


Rex  Creek— Continued. 

6324 — Continued. 

Terebratula  sp. 

Ostrea  sp. 

Anomia  sp. 

Inoceramus  sp. 

Nucula  sp. 

Area  sp. 

Undetermined  Gastropoda. 

Phylloceras  sp. 

Shark’s  teeth. 

Well  up  in  the  Kennicott  formation. 

6425— 

Serpula  sp. 

Ostrea  sp. 

Pecten  sp. 

Area  sp. 

Cyprina?  sp. 

Corbula  sp. 

Aporrhais  sp. 

Chemnitzia?  sp. 

Crioceras?  sp. 

6426- 

Fragment  of  large  ammonite. 

Higher  in  the  formation  than  6324. 

6336— 

Undetermined  fragmentary  ammonite. 

White  Creek : 

6327— 

Ostrea  sp. 

Upper  part  of  Kennicott  formation. 

6328— 

Fragment  of  large  ammonite. 

High  up  in  the  Kennicott. 

Young  Creek  : 

6329— 

Cyprina?  sp.  (fragment). 

The  absence  of  Aucella  from  the  collections  of  1909  raises  a ques- 
tion concerning  the  Kennicott  that  can  not  be  answered  with  the  data 
at  hand.  If,  as  seems  probable,  its  absence  is  due  merely  to  the  fail- 
ure to  find  it,  there  is  no  reason  to  suspect  any  difference  in  age  of 
the  Kennicott  sediments  east  and  west  of  Kennicott  Glacier.  If,  on 
the  other  hand,  it  does  not  occur  east  of  Kennicott  Glacier,  the  pos- 
sibility that  the  basal  Kennicott  beds  west  of  the  glacier  are  older  or 
that  the  sediments  of  the  two  localities  are  not  correctly  correlated  is 
apparent. 

It  will  be  seen  from  the  table  of  correlation  (pp.  26-27)  that 
Jurassic  sediments  are  widespread  in  Alaska.  They  are  found  along 
the  Pacific  coast  side  from  southeastern  Alaska  to  the  peninsula,  and 
again  on  the  Arctic  slope,  but  are  not  known  in  the  Yukon  Basin. 


42 


THE  NIZINA  DISTRICT,  ALASKA. 


Attention  is  directed  more  particularly  to  the  Nabesna-White  district, 
the  Matanuska  and  Talkeetna  district,  and  the  region  of  Cook  Inl-et 
and  the  Alaska  Peninsula. 

The  Nutzotin  Mountains,  northeast  of  the  Wrangell  group,  consist 
of  a great  thickness  of  banded  slates,  graywackes,  and  conglomerates 
associated  with  limestone  and  sandstone  beds  in  minor  amount. 
Upper  Jurassic  fossils  were  collected  from  these  beds,  but  the  beds 
are  very  imperfectly  known,  and  it  is  highly  probable  that  they  in- 
clude also  Triassic  or  even  older  beds.  They  are  exposed  in  the 
canyon  of  Chisana  River  for  a distance  of  18  miles,  and,  although 
they  are  much  folded,  it  is  evident  that  their  thickness  is  great. 

Lower  Middle  Jurassic  and  middle  and  upper  Middle  Jurassic 
sediments  occupy  extensive  areas  in  the  region  of  Matanuska  and 
Talkeetna  rivers.®  The  lower  Middle  Jurassic  rocks  have  a thickness 
of  2,000  feet,  more  or  less,  and  consist  of  shales,  sandstone,  and  con- 
glomerate, with  coal,  associated  with  andesitic  greenstone,  tuffs, 
agglomerates  and  breccias,  rhyolites,  dacites,  and  tuffs.  On  these 
was  deposited  unconformably  more  than  2,000  feet  of  middle  and 
upper  Middle  Jurassic  shales,  sandstones,  conglomerates,  tuff,  and 
arkose,  with  coal.  More  than  1,000  feet  of  this  is  conglomerate. 

The  Jurassic  rocks  of  Cook  Inlet  and  the  Alaska  Peninsula  were 
studied  by  Stanton  and  Martin  in  1904 6 and  again  by  Martin  in  the 
region  of  Iliamna  Bay  in  1909.  They  include  rocks  of  Lower,  Middle, 
and  Upper  Jurassic  age.  The  deposits  referred  to  the  Lower  Jurassic 
consist  chiefly  of  water-laid  tuffs,  and  are  found  at  Seldovia,  on  the 
east  side  of  Cook  Inlet*  and  probably  on  the  west  side  also.  The 
Middle  Jurassic  sediments,  called  by  Stanton  and  Martin  the  Enoch- 
kin  formation,  include  shale  and  sandstone,  with  a few  thin  beds  of 
limestone  and  conglomerate,  and  reach  a thickness  of  2,415  feet  on 
the  shore  of  Chinitna  Bay.  This  section  does  not  include  the  lower 
part  of  the  Enochkin  formation,  yet  the  thickness  given  represents 
what  is  probably  the  average  thickness  of  the  formation.  Upper 
Jurassic  sediments  succeeded  the  Enochkin  formation.  They  were 
first  described  by  Spurr®  and  received  their  formation  name  from 
Naknek  Lake.  The  Naknek  formation  includes  shale,  sandstone, 
conglomerate,  arkose,  tuff,  and  andesite.  A thickness  of  5,137  feet 
of  rocks  belonging  to  this  formation  was  measured  by  Stanton  and 
Martin  on  the  north  shore  of  Chinitna  Bay.  Lower,  Middle,  and 
Upper  Jurassic  deposits  thus  reach  a thickness  of  7,500  to  8,500  feet 
in  this  region. 

a Paige,  Sidney,  and  Knopf,  Adolph,  Geologic  reconnaissance  in  the  Matanuska  and  Tal- 
keetna basins,  Alaska  : Bull.  U.  S.  Geol.  Survey  No.  327,  1907,  pp.  16  and  following. 

6 Stanton,  T.  W.,  and  Martin,  G.  C.,  Mesozoic  section  on  Cook  Inlet  and  Alaska  Penin- 
sula : Bull.  Geol.  Soc.  America,  vol.  16,  1905,  pp.  391-410. 

c Spurr,  J.  E.,  A reconnaissance  of  southwestern  Alaska  : Twentieth  Ann.  Rept.  IT.  S. 
Geol.  Survey,  pt.  7,  1900,  pp.  169-171. 


SEDIMENTARY  ROCKS. 


43 


It  has  been  seen  from  the  brief  description  given  that  the  Jurassic 
section  is  more  nearly  complete  as  it  is  traced  westward  from  the 
Chitina  Valley.  The  evidence  is  too  incomplete  to  draw  definite  con- 
clusions, but  it  appears  that  about  the  lower  part  of  Cook  Inlet 
Lower,  Middle,  and  Upper  Jurassic  sediments  are  present,  that  in 
the  Talkeetna  and  Matanuska  district  the  Lower  Jurassic  is  lacking, 
and  that  in  the  Chitina  Valley  both  Lower  and  Middle  Jurassic  are 
absent.  A possible  explanation  of  this  condition  is  that  the  invasion 
of  the  Jurassic  sea  was  from  the  west  and  that  the  successive  drop- 
ping out  of  the  lower  members  from  the  stratigraphic  section  is  evi- 
dence of  progress  in  the  eastward  advance.  This  explanation,  how- 
ever, is  not  the  only  one,  for  the  lower  divisions  of  the  Jurassic  may 
yet  be  found  in  the  Chitina  Valley,  or  they  may  have  been  removed 
by  erosion  if  ever  present.  In  this  connection,  also,  attention  may 
once  more  be  drawn  to  the  fact  that  the  known  Jurassic  sediments 
of  Alaska  are  found  on  its  Arctic  and  Pacific  sides.  They  have  not 
been  discovered  in  the  Yukon  Basin. 

QUATERNARY  SYSTEM. 

PREGLACIAL  CONDITIONS. 

So  far  as  known,  the  region  under  discussion  was  elevated  above 
sea  level  at  the  end  of  Eocene  time  and  has  ever  since  remained  a land 
area.  During  and  after  the  cessation  of  the  mountain-building  proc- 
esses which  raised  the  land  to  its  present  elevation  stream  erosion  was 
active  and  well-developed  drainage  systems  were  formed,  the  area  and 
distribution  of  which  were  perhaps  very  much  as  they  are  to-day.  The 
topography  of  the  land  surface  and  the  arrangement  of  the  smaller 
drainage  lines  must,  however,  have  been  greatly  different  from  those 
existing  at  present.  The  relief  was  developed  by  stream  erosion,  and 
in  a region  of  such  great  relief  the  streams  must  have  occupied  narrow 
V-shaped  valleys,  with  the  spurs  between  the  lateral  tributary  val- 
leys overlapping  m such  a way  as  to  give  the  streams  a somewhat 
sinuous  course  around  the  points  of  the  interlocking  spurs.  Further- 
more, there  must  have  been  a heavy  covering  of  residual  soil  and  rock 
waste  mantling  the  ridges.  Stream  erosion  was  the  controlling  factor 
in  the  development  of  the  topography  up  to  the  beginning  of  Pleisto- 
cene time. 

PLEISTOCENE  (“  GLACIAL  ”)  EPOCH. 

CHARACTER  AND  EXTENT  OF  GLACIATION. 

A change  in  climatic  conditions  inaugurated  the  Pleistocene  epoch, 
with  a lowering  of  the  temperature  or  an  increase  in  precipitation,  or 
both.  Ice  began  to  form  in  the  heads  of  the  more  favorably  situ- 
ated vallej^s,  and  with  the  gradual  accumulation  of  ice  glacial 
movement  was  started.  The  small  glaciers  which  formed  in  the 
heads  of  a great  number  of  separate  valleys  moved  gradually  down- 


44 


THE  NIZINA  DISTRICT,  ALASKA. 


ward  to  meet  and  merge  in  the  main  valleys.  Three  primary  glaciers 
existed  within  the  limits  of  this  district,  two  of  them  (in  the  Kenni- 
cott  and  the  Nizina  valleys)  moving  southward  and  one  (in  the 
Chitina  Valley)  moving  westward. 

It  is  possible  that  the  Pleistocene  epoch  has  been  represented  in 
these  mountains  by  more  than  one  great  ice  advance,  with  interglacial 
epochs  in  which  the  ice  diminished  greatly  in  area  and  may  even 
have  disappeared  in  large  part.  No  direct  evidence  has  been  obtained 
that  this  was  the  case  in  Alaska,  as  the  last  great  ice  advance  oblit- 
erated all  evidence  of  previous  advances.  In  other  mountain  regions 
in  the  United  States  and  Canada  a succession  of  ice  advances  has 
been  established,  and  somewhat  similar  conditions  have  probably 
prevailed  in  Alaska.  The  effects  of  earlier  ice  invasions  may  have 
had  an  important  influence  upon  the  erosion  of  the  deep  glacial  val- 
leys of  this  region,  but  the  immediate  effects  now  remaining,  such  as 
the  distribution  of  moraines  and  glacial  gravels,  are  to  be  ascribed  to 
the  action  of  the  last  great  glaciers  which  filled  these  valleys. 

As  already  stated,  the  dissection  of  the  area  in  preglacial  time 
had  been  accomplished  by  normal  stream  erosion.  Great  quanti- 
ties of  soil  and  rock  waste  were  ready  at  hand  for  the  glaciers,  and 
these  materials  were  incorporated  into  the  advancing  ice  tongues 
and  served  as  abrasives  for  the  glaciers  to  use  in  the  further  grind- 
ing out  of  their  beds.  As  they  advanced  down  their  valleys  they 
encountered  opposition  from  the  spurs  which  projected  into  the  val- 
leys, and  as  the  ice  was  able  to  override  these  spurs  it  was  upon 
them  that  its  erosion  was  most  effective.  This  selective  erosion  of 
projecting  bodies  of  rock  was  carried  on  continuously,  and  the 
resultant  is  the  broad,  U-shaped,  troughlike  gorge  which  is  recog- 
nized as  the  evidence  of  severe  glacial  erosion.  Erosion  in  the  val- 
leys, however,  was  not  confined  to  the  removal  of  overlapping  spurs. 
The  rock  fragments  held  in  the  bottoms  of  the  glaciers  and  pressed 
down  upon  their  floors  by  the  weight  of  several  thousand  feet  of  ice 
formed  admirably  adapted  tools  for  grinding  down  the  floors  and 
rasping  away  the  walls.  * It  is  impossible  to  estimate  with  any  degree 
of  accuracy  the  amount  of  glacial  deepening  which  the  trunk  valleys 
have  undergone.  The  difference  in  elevation  between  the  mouth  of  a 
hanging  tributary  valley  and  the  floor  of  the  main  valley  below  may 
be  considered  to  offer  a fair  basis  for  estimating  this  deepening,  and  in 
many  places  this  discordance  is  from  1,000  to  1,500  feet.  Some  such 
figure  may  well  represent  the  depth  to  which  glacial  scour  has  low- 
ered the  larger  valleys. 

At  the  time  of  the  last  great  period  of  glaciation  the  Nizina  re- 
gion was  invaded  by  an  ice  flood  which  covered  it  to  such  an  extent 
that  the  surface  relief  within  the  area  was  not  more  than  4,500  feet 
as  compared  with  more  than  7,700  feet  at  the  present  time.  Only 


SEDIMENTARY  ROCKS. 


45 


the  high  ridges  between  the  principal  drainage  lines  projected  above 
the  surface  of  the  ice  streams.  The  land  areas  were  restricted  to 
narrow,  angular  masses  of  irregular  outline  cut  into  on  all  sides  by 
the  smaller  glaciers,  which  headed  back  toward  the  crests  of  the 
divides.  An  attempt  has  been  made  (PL  III,  in  pocket)  to  outline 
the  land  areas  which  projected  above  the  glaciers.  This  outline  can 
not  be  considered  as  exact,  but  it  must  represent  with  a fair  degree 
of  accuracy  the  areas  which  stood  up  above  the  ice  surface.  Of  the 
total  area  of  the  Nizina  special -map  (300  square  miles)  only  about  18 
square  miles  remained  unglaciated. 

The  depth  at  which  the  ice  stood  in  the  different  valleys  can  in 
favorable  places  be  determined  rather  closely  by  the  present  distri- 
bution of  glacial  moraines  and  erratic  bowlders  and  by  the  shapes 
of  the  eroded  valley  walls.  Certain  mountains,  we  know,  must  have 
stood  above  the  glaciers,  because  of  the  angular,  rugged  character  of 
their  summits,  which  fail  to  show  the  effects  of  the  abrasive  action 
of  the  ice.  Other  mountains,  we  know,  must  have  been  overridden  by 
the  ice,  because  of  their  smoothed  and  rounded  outlines  and  because 
of  the  occurrence  on  their  tops  of  glacial  bowlders  of  rocks  which 
occur  in  place  nowhere  in  the  vicinity  of  their  present  resting  places. 
From  such  evidence  it  is  found  that  in  Nizina  Valley,  at  Sourdough 
cabins,  the  top  of  the  glacier  must  have  stood  more  than  3,000  feet 
above  the  present  river  flat. 

CHITINA  GLACIER. 

The  Chitina  Valley,  which  extends  from  the  head  of  Chitina  River 
near  the  international  boundary  in  a west-northwest  direction  to  the 
Copper  River  basin,  is  the  channel  which  drained  all  the  ice  fields 
from  the  south  side  of  the  Wrangell  Mountains  as  well  as  those  from 
the  north  slope  of  the  Chugach  Range.  Although  only  one  edge  of 
the  Chitina  Glacier  lay  within  the  area  of  the  Nizina  special  map,  it 
may  not  be  out  of  place  to  give  here  some  idea  of  the  size  of  this 
ice  tongue  as  a whole.  At  its  maximum  it  was  about  120  miles  long 
in  its  own  valley,  and  it  joined  the  Copper  River  Glacier,  the  length 
of  which  below  the  junction  of  the  Chitina  is  not  known,  although 
it  must  have  been  considerable.  The  ice  field  had  a width  for  portions 
of  its  course  of  20  miles  and  averaged  about  12  miles,  so  that  its 
total  area  was  not  far  from  1,500  square  miles,  exclusive  of  all  tribu- 
tary glaciers.  South  of  this  area  it  was  certainly  close  to  4,000  feet 
in  thickness  and  may  have  been  much  thicker.  On  account  of  its 
great  thickness  the  ice  surmounted  the  divide  between  Chitina  River 
and  Young  Creek  and  pushed  to  the  northwest,  covering  the  ridge 
between  Young  and  Chititu  creeks,  so  that  the  northern  boundary  of 
this  great  ice  field  was  here  the  high  mountain  ridge  north  of  White 
Creek.  That  it  completely  covered  the  high  divides  south  of  this 


46 


THE  NIZINA  DISTRICT,  ALASKA. 


ridge  is  evident  not  only  from  the  smoothed  Rnd  subdued  slopes 
of  their  summits  but  from  the  presence  on  them  of  scattered  bowl- 
ders of  rocks  strange  to  this  immediate  vicinity.  In  Chititu  and 
White  creeks  there  are  numerous  bowlders  of  greenstone,  although 
none  occurs  in  place  within  this  drainage  basin.  Their  presence 
here  as  well  as  that  of  the  native  copper  and  silver  found  in  the 
placer  gravels  is  doubtless  due  to  the  transportation  of  glacial  ice, 
the  bowlders  in  White  Gulch  having  been  brought  from  the  east  by 
the  Chitina  Glacier,  and  the  bowlders  in  Rex  and  Chititu  creeks 
either  by  the  same  ice  tongue  or  from  the  north  by  the  Nizina  Glacier. 
Much  of  the  native  copper  and  greenstone  of  Young  Creek  was 
brought  in  by  the  Chitina  Glacier,  although  there  may  be  greenstone 
in  place  at  the  head  of  this  creek.  There  is  still  a large  glacier  at 
the  head  of  Chitina  Valley,  though  little  is  known  of  its  length  or 
appearance. 

NIZINA  GLACIER. 

The  head  of  the  Nizina  Basin  is  still  occupied  by  a great  glacier, 
which  now  terminates  about  11  miles  above  the  mouth  of  Chitistone 
River.  The  valley  below,  however,  shows  strongly  the  erosion  of  the 
former  glacier  which  moved  down  it.  Tributary  ice  tongues  entered 
the  valley  from  both  sides  north  of  the  area  here  considered,  but 
within  it  the  large^  branches  all  came  in  from  the  east.  The  north- 
ernmost and  by  far  the  most  important  branch  came  down  the  Chit- 
istone Valley.  This  stream  drains  a basin  which  extends  northeast 
to  Skolai  Pass  and  east  into  a range  of  high  glaciated  mountains. 
That  the  valley  was  the  outlet  for  a vigorous  glacier  is  evident  from 
the  steep-walled  trough  through  which  the  stream  now  flows.  The 
valley  floor  near  the  mouth  of  the  canyon  is  only  three-eighths  mile 
wide,  but  the  ice  in  it  once  reached  a depth  of  at  least  3,500  feet  and 
was  able  to  keep  its  trough  cut  down  to  grade  with  the  floor  of  the 
Nizina  Valley.  Toward  the  lower  end  of  the  Chitistone  Valley  the 
tops  of  the  mountains  on  both  the  north  and  the  south  sides  are  flat 
and  mesa-like,  and,  although  the  valley  glacier  did  not  extend  up  to 
these  mesas,  they  were  occupied  by  glaciers  which  must  have  extended 
to  their  edges  and  cascaded  down  upon  the  valley  glacier  below,  so 
that  only  a portion  of  the  steep  cliffs  at  the  upper  limit  of  the  valley 
walls  were  free  from  ice. 

Five  miles  south  of  the  Chitistone  a tributary  ice  tongue  fed  into 
the  Nizina  from  Dan  Creek.  This  lobe  drained  the  ice  from  a much 
smaller  basin  than  the  Chitistone  and  excavated  its  valley  much  less 
severely.  In  it  the  depth  of  the  ice  was  great,  but  this  was  due  more 
to  the  damming  back  by  the  great  glacier  in  the  Nizina  Valley  than 
to  its  own  supply,  and  the  movement  must  have  been  comparatively 
sluggish.  Besides  receiving  ice  from  a large  number  of  cirques,  some 


SEDIMENTARY  ROCKS. 


47 


of  which  are  still  occupied  by  small  glaciers,  this  lobe  was  fed  by  the 
ice  sheet  on  the  mesa  to  the  north.  This  ice  sheet  still  exists  and 
covers  most  of  the  flat  uplands,  but  now  sends  ice  over  its  edge  at 
only  a few  points. 

The  main  valleys  of  Chititu  and  Young  creeks  were  invaded  by 
ice  from  the  Chitina  Glacier,  which  spread  over  the  intervening  ridges 
and  made  a continuous  ice  sheet  from  Chititu  Creek  to  the  south  side 
of  the  Chitina  Valley.  Rex  Creek,  however,  was  separated  by  a high 
ridge  from  the  Chitina  ice  and  sent  down  a tributary  tongue  to  join 
the  great  ice  flood  at  the  junction  of  the  Nizina  and  Chitina  glaciers. 

KENNICOTT  GLACIER. 

The  Kennicott  Basin  is  occupied  in  its  upper  portion  by  a glacier 
which  extends  within  5 miles  of  the  mouth  of  Kennicott  River.  The 
area  of  the  Nizina  special  map  includes  about  10  square  miles  of  the 
eastern  edge  of  this  ice  tongue.  A line  drawn  from  Kennicott  to  the 
point  of  junction  of  the  two  principal  branches  of  the  glacier  sepa- 
rates the  white  ice  of  the  east  fork  from  the  moraine-covered  ice  of 
the  lower  portion.  The  west  fork,  which  is  the  larger,  heading  on  the 
flanks  of  Mount  Blackburne,  shows  a banded,  ribbon-like  surface  of 
lines  of  white  ice  alternating  with  long  surface  moraines.  Below  the 
junction  of  the  two  branches  the  white  bands  disappear  and  the 
glacier  presents  a chaotic  surface  of  sharp  hills  and  deep,  wide- 
mouthed crevasses,  all  more  or  less  thickly  covered  with  debris.  Part 
of  the  drainage  from  the  melting  ice  runs  off  as  streams,  which  flank 
the  lower  portion  of  the  glacier  on  either  side,  but  much  the  greater 
part  of  the  water  emerges  from  what  is  known  as  the  “ pothole,”  at 
the  lower  end  of  the  glacier.  The  pothole  is  the  mouth  of  a subglacial 
channel,  and  Kennicott  River  boils  out  of  this  opening  as  a gigantic 
spring.  In  winter  the  pothole  has  been  known  to  freeze  up,  damming 
back  the  water  until  sufficient  hydraulic  pressure  has  been  developed 
to  break  away  the  ice,  wdien  a torrent  of  water  rushes  down  Kennicott 
and  Nizina  rivers,  sometimes  flooding  the  ice  all  the  way  to  Copper 
River. 

The  severity  of  the  earlier  glaciation  in  the  Kennicott  Valley  is 
comparable  to  that  of  the  Nizina.  The  ice  extended  southward  to 
join  the  great  Chitina  Glacier,  which  had  already  been  swelled  by  the 
ice  from  the  Nizina.  The  surface  of  the  glacier  at  Kennicott  then 
stood  about  3,000  feet  higher  than  it  does  to-day,  and  the  severity  of 
its  erosion  is  shown  by  the  straight  lines  of  the  contours  along  the 
mountain  sides  and  by  the  complete  absence  of  projecting  spurs. 

The  Kennicott  Glacier  had  within  this  area  one  important  tributary, 
which  occupied  the  valley  of  McCarthy  Creek.  Its  course,  like  that 
of  the  Kennicott  and  Nizina  glaciers,  was  from  north  to  south,  and 
its  erosion  was  sufficient  to  reduce  its  valley  to  a straight,  U-shaped 


48 


THE  NIZINA  DISTRICT,  ALASKA. 


trough.  Within  the  area  of  this  map  all  the  important  tributaries 
to  McCarthy  Creek  Glacier  came  in  from  the  east,  especially  from 
the  valleys  of  Nikolai  Creek  and  East  Fork.  At  one  time  the  ice 
surface  stood  1,000  feet  above  the  divide  at  the  head  of  South  Fork 
of  Nikolai  Creek,  and  it  is  probable  that  some  of  the  ice  from  the 
Nizina  Glacier  moved  westward  over  this  col  and  then  down  the 
McCarthy  Creek  valley.  Below  Sourdough  Peak  the  Kennicott, 
McCarthy,  and  Nizina  glaciers  all  joined  the  great  Chitina  ice  stream 
and  moved  northwestward  down  the  Chitina  Valley. 

In  the  preceding  paragraphs  the  attempt  has  been  made  to  describe 
the  glaciers  of  the  region  at  the  time  of  their  greatest  development. 
The  individual  ice  lobes  and  their  interrelations  would  have  been 
different  at  lesser  stages  of  development.  The  arrows  shown  on  the 
map  (PL  III,  in  pocket)  represent  the  directions  of  ice  movement  in 
the  different  parts  of  the  area. 

RETREAT  OF  THE  ICE. 

In  the  earlier  stages  of  glaciation  of  the  region  the  ice  no  doubt 
built  up  lateral  and  terminal  moraines,  but  further  advances  de- 
stroyed or  obliterated  all  traces  of  the  earlier  deposits.  It  is  only 
those  deposits  that  were  laid  down  at  the  time  of  or  subsequent  to 
the  maximum  advance  of  the  ice  that  have  been  preserved,  and  in 
many  jilaces  even  this  material  has  been  removed  by  stream  cutting 
or  been  covered  with  stream  deposits.  There  are  left  only  a few 
areas  of  distinctive  terminal  moraine,  having  the  characteristic  hum- 
mock and  kettle  topography.  Some  such  moraine  still  exists  west  of 
the  lower  portion  of  Young  Creek,  and  some  east  of  lower  Chititu 
Creek,  with  occasional  more  recent  patches  like  that  on  Texas  Creek 
near  the  head  of  Copper  Creek.  These  areas  often  contain  lakes 
which  occupy  undrained  depressions  in  the  glacial  deposits.  The 
absence  of  strong  moraines  in  most  of  the  valleys  is  due,  in  part  at 
least,  to  the  vigorous  cutting  of  the  streams,  which  have  long  ago 
removed  them.  The  Kennicott  Glacier,  which  terminates  near  the 
mouth  of  McCarthy  Creek,  has  remarkably  little  fnoraine  around  its 
edges,  and  although  the  surface  of  the  lower  portion  of  the  glacier 
is  covered  with  detritus  the  streams  have  removed  this  as  fast  as  it 
has  been  dropped  by  the  ice  and  in  many  places  are  cutting  into  the 
glacier  itself. 

Glacial  till  or  bowlder  clay  is  rather  widely  distributed  in  this 
area  along  the  lower  slopes  of  the  valley  walls.  Its  surface  is  gen- 
erally covered  by  a heavy  growth  of  mosses  and  timber,  but  fresh 
exposures  can  be  seen  at  many  places  along  the  banks  of  streams. 
It  consists  of  a rather  dense  blue  clay  in  which  are  embedded  bowl- 
ders, pebbles,  and  angular  fragments  of  many  different  kinds  of 
rock,  and  it  is  characterized  by  unassorted  materials  and  lack  of 
stratification. 


SEDIMENTARY  ROCKS. 


49 


BENCH  GRAVELS. 

As  climatic  conditions  became  less  favorable  for  glaciation  and  the 
ice  diminished  from  its  greatest  thickness  the  glaciers  in  many  of 
the  smaller  drainage  lines  tributary  to  the  larger  trunk  valleys 
shrank  until  they  no  longer  joined  the  main  ice  lobes  below.  Thus 
the  lower  part  of  McCarthy  and  Dan  creek  valleys  were  free  from 
ice  while  their  mouths  were  blockaded  by  the  Kennicott  and  the 
Nizina  glaciers.  In  like  manner  the  ice  in  the  Chitina  Valley  had 
shrunk  so  that  it  was  no  longer  able  to  override  the  ridges  on  either 
side  of  Young  Creek,  and  Chititu  and  Young  creeks  had  lost  their 
ice  while  the  Nizina  Glacier  still  stood  high  in  the  valley  to  the 
northwest.  As  a result  the  drainage  in  many  valleys  was  impeded 
by  the  ice  dams  across  their  mouths,  and  the  streams  began  to 
fill  in  their  basins  with  gravel  deposits.  It  may  be  that  temporary 
lakes  were  sometimes  formed  behind  the  ice  barriers,  but  the  char- 
acter of  the  gravel  deposited  indicates  that  if  such  lakes  existed 
they  must  have  been  of  short  duration. 

Gravel  fillings  behind  glacier  dams  in  many  places  reached  a 
great  thickness.  In  Young  Creek  valley,  above  the  portion  where 
the  creek  flows  nofth,  the  gravels  are  in  places  more  than  500  feet  thick 
near  the  center  of  the  valley  and  thin  out  at  the  sides.  The  upper 
limit  of  the  gravels  is  difficult  to  determine  on  account  of  the  thick 
coating  of  moss  with  which  the  surface  is  covered,  but  it  probably 
lies  for  the  most  part  between  the  elevations  of  3,250  and  3,500  feet. 
In  Chititu  Creek,  at  the  mouth  of  Rex  Creek,  a similar  thickness  of 
gravels  was  reached.  At  the  point  where  Dan  Creek  emerges  from 
the  mountains  a great  bench  more  than  TOO  feet  high  shows  that 
the  stream  floor  was  graded  up  to  that  level  when  the  Nizina  Glacier 
still  filled  the  valley  below.  In  the  McCarthy  Creek  valley  a broad 
area  was  filled  with  gravels  deposited  under  similar  conditions.  An 
advance  by  the  Kennicott  Glacier  of  only  2 or  3 miles  would  be 
sufficient  to  cause  McCarthy  Creek  to  begin  again  the  grading  up  of 
its  valley  with  gravels  like  those  of  which  the  gravel  benches  are 
composed. 

In  all  of  the  valleys  mentioned  the  alluvial  filling  was  due  to  the 
presence  of  an  ice  barrier  which  retarded  the  drainage  and  caused 
the  streams  to  build  rapidly.  As  the  great  glaciers  retreated  and 
their  thickness  decreased  the  barriers  to  the  tributary  streams  were 
lowered  and  they  began  to  cut  into  the  gravel  filling  which  they  had 
laid  down.  They  did  not,  however,  remove  the  filling  from  the  whole 
width  of  the  valleys,  but  intrenched  themselves  in  this  filling  and 
developed  deep  gorges  with  gravel  banks.  Throughout  much  of  the 
upper  part  of  Young  Creek  and  in  parts  of  Chititu,  Dan,  and 
McCarthy  creeks  the  streams  have  now  cut  completely  through  the 
70648°— Bull.  448—11 4 


50 


THE  NIZINA  DISTRICT,  ALASKA. 


gravels  and  into  the  rock  below,  leaving  the  valley  filling  as  terraces 
or  benches  on  either  side  of  the  streams.  In  Young  Creek  valley, 
especially,  many  lateral  tributaries  have  also  cut  through  the  gravels, 
which  now  form  interrupted  benches  along  the  slopes  to  the  north 
and  south  of  the  stream. 

PRESENT  STREAM  GRAVELS. 

The  larger  glacier-fed  streams  of  the  area  are  in  sharp  contrast, 
both  in  appearance  of  water  and  in  character  of  valley  deposits,  with 
the  streams  which  do  not  head  in  active  glaciers.  The  streams  which 
are  supplied  only  by  melting  snow  and  by  the  ordinary  run-off  are 
for  the  most  part  clear,  and  they  are  gradually  cutting  their  valleys 
deeper.  The  glacier- fed  streams,  on  the  contrary,  are  supplied  with 
great  quantities  of  detritus  by  the  glaciers,  and  during  the  warm 
season  they  are  turbulent  and  heavily  loaded,  so  that  they  are  con- 
stantly building  up  their  vallej^s  with  gravels  and  silts  brought  down 
from  above.  The  Nizina  Valley  is  a conspicuous  example  of  this 
building  process.  The  present  flood  plain  ranges  in  width  from  one- 
fourth  mile  at  the  extreme  western  edge  of  the  area  mapped  to  more 
than  2 miles  at  its  widest  points.  The  flat  is  composed  of  gravel 
bars,  for  the  most  part  bare  of  vegetation  though  some  of  the  higher 
portions  are  timbered.  The  proportion  of  the  flat  that  is  covered  by 
water  at  any  one  time  not  only  varies  greatly  with  the  seasons,  but 
often  there  is  a great  daily  range  as  well.  Since  the  water  supply  is 
largely  furnished  by  the  melting  of  the  glaciers  and  of  the  snow  on 
the  mountains,  the  streams  are  highest  in  July,  and  in  periods  of 
high  water  a large  part  of  the  flat  is  covered.  During  the  late  fall 
and  winter  the  rivers  dwindle  until  but  little  water  flows  beneath  the 
ice.  The  daily  range,  too,  is  largely  controlled  by  the  temperature, 
the  streams  being  lowest  in  the  earty  morning  but  on  bright,  sunny 
days  increasing  in  volume  until  the  late  afternoon,  when  the  flow  is 
many  times  as  large  as  it  was  early  in  the  day. 

All  of  these  variations  in  volume  are  important  factors  in  the  trans- 
portation and  deposition  of  debris.  In  high  stages  the  streams  are 
most  turbulent  and  great  quantities  of  gravel  and  silt  are  carried  by 
them.  In  low  stages  the  water  becomes  clearer  and  but  little  mate- 
rial is  moved.  As  a result  of  their  overloaded  condition  during  the 
summer,  the  streams,  which  flow  in  some  places  as  single  streams  and 
in  others  as  intricate  networks  of  channels,  are  constantly  shifting 
their  courses  over  the  flood  plains,,  building  up  bars  in  some  places 
while  cutting  them  away  in  others.  In  the  Nizina  Valley  below 
Young  Creek  the  present  tendency  of  the  river  is  to  lower  its  bed, 
owing  to  the  increased  gradient  given  by  the  cutting  down  of  Nizina 
Canyon  below.  Above  Young  Creek  the  valley  floor  is  being  built 


SEDIMENTARY  ROCKS. 


51 


up,  the  building  proceeding  most  rapidly  at  the  mouths  of  the  tribu- 
tary streams.  Chititu  Creek  has  a large  low-grade  fan  below  its 
canyon,  but  the  edge  of  this  fan  has  reached  the  Nizina  flood  plain  at 
only  one  point.  Dan  Creek  also  has  a low  fan  extending  out  to  the 
Nizina  bars.  The  largest  deposit  from  a tributary  stream  is  that  at 
the  mouth  of  Chitistone  River.  Here  a wide  fan  of  low  slope  has 
crowded  Nizina  River  over  against  the  rock  cliffs  on  its  west  valley 
wall,  where  in  places  all  the  talus  slopes  have  been  removed  and  the 
flood  plain  extends  flush  up  against  the  limestone  cliffs.  This  fan 
has  also  been  effective  in  retarding  the  current  of  Nizina  River  above 
it  and  in  aiding  deposition  there. 

McCarthy  Creek  flows  for  the  lower  10  miles  of  its  course  through 
a more  or  less  narrow  valley  intrenched  into  the  gravel  deposits  and 
into  its  rock  bed,  but  above  this  portion  the  valley  floor  is  broad  and 
gravel  filled. 

POSTGLACIAL  EROSION. 

The  agencies  of  rock  weathering  and  erosion  are  very  active  in 
this  region  of  great  daily  ranges  in  temperature,  high  altitudes,  and 
steep  slopes,  so  that  the  amount  of  rock  material  which  has  been 
removed  since  the  retreat  of  the  great  glaciers  has  been  large.  The 
timber  line  throughout  the  district  lies  at  about  4,000  feet  or  lower, 
although  willow  and  alder  bushes  flourish  above  this  and  are  some- 
times found  up  to  an  elevation  of  5,000  feet.  Above  5,000  feet  vege- 
tation is  sparse  and  most  of  the  surface  is  bare  and  exposed  to  the 
agencies  of  weathering.  Large  talus  slopes  occur  below  all  steep 
cliffs.  The  greenstone  is  perhaps  most  resistant  of  all  rocks  in  this 
vicinity,  and  the  talus  accumulations  below  greenstone  outcrops  are 
small  as  compared  with  those  below  similar  cliffs  of  the  more  easily 
weathered  rocks.  The  Chitistone  limestone  follows  the  greenstone 
in  its  ability  to  resist  weathering,  although,  as  is  to  be  expected,  there 
are  often  large  talus  slopes  below  the  enormous  cliffs  which  this  lime- 
stone offers.  The  porphyry  weathers  much  more  rapidly  than  either 
greenstone  or  limestone,  and  the  sides  of  those  mountains  which  are 
composed  of  this  rock  are  almost  invariably  buried  beneath  great 
talus  aprons.  In  the  steep-sided  porphyry  mountain  between  the 
Kennicott  and  McCarthy  Creek  the  talus  is  so  abundant  that  few 
outcrops  occur  below  an,  elevation  of  5,000  feet  and  only  the  upper 
craggy  portion  of  the  mountain  is  free  from  talus.  Both  Triassic 
and  Jurassic  shales  weather  readily,  the  latter  with  the  greater 
ease  on  account  of  its  freedom  from  hard  beds  of  limestone.  A 
great  amount  of  postglacial  stream  cutting  has  been  done  in  the 
Triassic  shales  between  McCarthy  Creek  and  the  Nizina.  In  the 
Kennicott  shales  of  Dan,  Chititu,  and  Young  creeks  the  amount  of 
stream  cutting  near  the  gulch  heads  has  been  very  large.  There  is 


52 


THE  NIZINA  DISTRICT,  ALASKA. 


every  reason  to  believe  that  on  the  south  side  of  Chititu  and  on  both 
sides  of  Young  Creek  the  slopes  were  left  smooth  and  free  from 
gulches  by  the  glacial  ice.  Since  the  ice  retreated  large  gulches  have 
been  cut  and  a great  amount  of  the  easily  eroded  shale  has  been 
removed.  The  streams  in  these  valleys  have  also  succeeded  in  cutting 
through  the  thick  gravels  into  the  bed  rock  below. 

Altogether,  when  the  comparatively  short  time  that  has  elapsed 
since  the  retreat  of  the  ice  from  this  area  is  considered,  the  work 
accomplished  by  erosional  agencies  has  been  surprisingly  great. 

ROCK  GLACIERS.® 

Among  the  important  agencies  of  postglacial  denudation  in  this 
district  are  the  remarkable  features  which  have  been  called  rock 
glaciers  (PI.  Ill,  in  pocket).  These  are  rather  widely  distributed 
among  the  more  rugged  portions  of  the  area,  more  than  30  occur- 
ring within  the  borders  of  this  sheet.  They  are  known  to  occur  in 
other  parts  of  the  Wrangell  Mountains,  but  here  they  attain  excep- 
tionally perfect  development.  An  inspection  of  the  topographic 
map  shows  at  once  many  of  the  characteristics  of  the  rock  glaciers, 
but  the  important  features,  such  as  the  surface  markings,  can  not 
be  shown  with  such  a large  contour  interval.  Although  differing 
greatly  among  themselves  in  size,  shape,  and  material,  they  have 
certain  characteristics  in  common.  They  are  usually  long,  narrow 
flows,  many  times  longer  than  wide,  confined  in  the  bottoms  of 
cirquelike  valleys.  Some  have  wide,  fan-shaped  heads  and  taper 
down  to  narrow  tongues  below;  others  are  narrow  above  and  spread 
out  into  spatulate  lobes  below;  but  the  greater  number  are  bodies 
of  nearly  uniform  width,  from  one-tenth  to  one-fourth  of  a mile 
wide  and  from  one-half  to  2^  miles  long.  The  surface  slopes  vary 
in  different  examples  from  9°  to  18°  for  the  whole  course  of  the  floiv. 

On  viewing  one  of  the  better-developed  rock  glaciers  one  is  struck 
by  its  great  resemblance  to  true  glaciers.  They  all  head  in  cirques 
and  extend  thence  down  the  valleys.  In  crass  section  their  shape  is 
much  like  that  of  a glacier,  being  highest  above  the  valley  axis  and 
sloping  down  sharply  on  the  sides.  Where  confined  in  narrow  valleys 
the  rock  glaciers  are  narrow  tongues  lying  in  the  valley  bottoms, 
but  upon  emerging  from  their  restricting  walls  they  spread  out  into 
broad  lobes.  Some  have  distinct  lateral  moraine-like  ridges  and  all 
show  a more  or  less  well-marked  longitudinal  ridging. 

The  materials  of  which  the  rock  glaciers  are  composed  are  the 
blocks  and  fragments  of  angular  rock  such  as  go  to  make  up  the 
ordinary  talus  slope,  the  fragments  being  derived  from  the  walls  of 
the  cirque  at  the  valley  head.  The  variety  of  rock  found  in  any 


Capps,  Stephen  R.,  Rock  glaciers  in  Alaska : Jour.  Geology,  vol.  18,  pp.  359—375. 


SEDIMENTARY  ROCKS. 


53 


rock  glacier  therefore  depends  on  the  materials  found  in  the  cirque 
walls — porphyry,  limestone,  greenstone,  or  shale,  as  the  case  may  be. 
The  individual  rock  fragments  vary  in  size  from  fine  stuff  to  blocks 
several  feet  in  diameter  in  exceptional  cases.  Six  inches  would  per- 
haps be  the  average  size  in  these  rock  glaciers  which  are  composed 
of  porphyry,  while  in  the  greenstones  and  limestones  the  average  is 
larger  and  in  the  shales  it  is  smaller  than  this. 

In  many  of  the  rock  glaciers  the  fragmental  rock  extends  all  the 
way  to  the  head  of  the  cirque,  with  no  ice  visible  and  little  or  no 
snow  on  the  surface.  In  several  cases,  however,  the  rock  glaciers 
grade  into  true  glaciers  at  their  upper  ends,  without  any  sharp  line 
of  demarcation,  so  that  there  is  a complete  gradation  between  the 
two. 

The  surface  markings  are  characteristic  and  in  some  measure  are 
systematic  in  their  arrangement.  In  the  upper  portions  there  are 
usually  many  parallel  longitudinal  ridges  a few  feet  high,  separated 
by  troughlike  depressions  (PI.  IX,  B , p.  56).  Toward  the  lower 
end  of  each  rock  glacier  which  has  an  opportunity  to  spread  out 
into  a broad  lobe  the  longitudinal  ridges  become  less  prominent  and 
finally  disappear  entirely,  giving  place  to  concentric  wrinkles  which 
parallel  the  borders  of  the  lobe.  The  sides  of  the  flow  below  the 
cirque  are  usually  separated  from  the  rock  valley  walls  by  a sharp 
trough,  and  at  their  lower  ends  the  flowTs  steepen  to  the  angle  of  rest 
for  the  material.  The  wThole  appearance  gives  one  a decided  impres- 
sion of  movement,  as  if  the  material  had  moved  forward  from  the 
cirques  in  somewhat  the  manner  of  a glacier,  the  longitudinal  lines 
simulating  moraine  lines. 

The  marked  resemblance  of  these  flows  to  glaciers  led  to  the  sus- 
picion that  ice  must  be  in  some  way  responsible  for  their  movement. 
To  determine  if  this  were  the  case,  a number  of  the  rock  glaciers,  7 
or  8 in  all,  were  dug  into,  and  in  each  instance  clear  ice  was  found. 
This  Avas  not  massive  ice  like  that  of  a glacier,  but  interstitial  ice, 
filling  the  cavities  between  the  angular  fragments  and  forming  with 
the  rock  a breccia,  with  the  ice  as  the  matrix.  The  depth  below  the 
surface  at  which  ice  was  found  A7aried  according  to  the  elevation  of 
the  rock  glacier  and  to  the  portion  of  it  examined.  Toward  their 
lower  ends  the  ice  lay  too  deep  to  be  found  by  any  shallow  excava- 
tions that  there  was  opportunity  to  make.  Farther  up,  toward  the 
cirques  in  which  they  head,  the  ice  was  usually  found  within  a foot 
or  two  of  the  surface  if  a depression  was  dug  into.  The  surface  of 
the  ice-filled  portion,  being  determined  by  the  depth  to  which  melt- 
ing takes  place,  follows  roughly  the  surface  of  the  flow,  so  that  along 
the.  troughs  between  the  ridges  running  water  could  be  found  on  a 
warm  day  following  shallow  channels  in  the  ice-filled  talus. 


54 


THE  NIZINA  DISTRICT,  ALASKA. 


The  rock  glaciers  are  quite  different  from  true  glaciers,  although 
in  those  cases  where  the  rock  glacier  is  a continuation  of  the  lower 
end  of  a true  glacier  it  may  be  impossible  to  draw  a line  separating 
the  two.  For  the  formation  and  existence  of  a glacier  it  is  necessary 
that  in  the  head  of  the  basin  occupied  by  ice  there  should  be  an 
annual  surplus  of  snowfall  over  melt.  When  the  amount  of  snow- 
fall becomes  less  than  the  amount  which  melts  and  runs  off,  the 
glacier  will  dwindle  and  finally  disappear.  The  greater  number  of 
rock  glaciers,  on  the  other  hand,  are  found  to  head  in  cirques  in 
which  all  or  practically  all  of  the  winter  snow  disappears  during  the 
summer.  In  a true  glacier,  no  matter  how  heavily  moraine  covered 
it  may  be,  there  is  always  a tendency  to  crevasse  where  the  ice  rounds 
a bend  or  passes  over  an  irregularity  of  its  bed,  and  great  irregularity 
of  surface  is  common  at  the  lower  end,  where  the  melting  ice  allows 
the  overlying  moraine  to  cave  in.  In  the  rock  glaciers  no  crevasses 
were  seen,  even  in  places  where  abrupt  changes  in  the  grade  of  the 
bed  occur,  and  large  cave-in  pits  are  wanting.  Irregularities  of  this 
kind,  however,  are  not  to  be  expected  if  the  rock  glaciers  are  com- 
posed, as  they  seem  to  be,  of  talus,  with  ice  only  in  the  interstices,  for 
the  talus  itself  is  self-supporting  without  the  ice,  and  the  shape  of  the 
surface  would  be  but  little  changed  if  the  ice  should  all  melt  out. 
This  is  true,  however,  only  of  those  flows  which  have  not  glaciers  at 
their  upper  ends.  Of  those  which  head  in  glaciers,  the  upper  ends 
would  of  course  be  profoundly  altered  by  the  melting  of  the  ice,  and 
these  effects  would  be  seen  just  as  far  down  the  flow  as  massive 
glacial  ice  had  existed.  The  rock  glaciers  differ  from  true  glaciers 
in  that,  although  they  advance  spasmodically,  they  never  retreat,  for 
the  flow  retains  its  form  even  after  the  ice  has  melted  out  and  motion 
has  ceased.  Little  has  been  published  concerning  features  of  this 
kind.  Certain  “ stone  rivers”  in  the  Falkland  Islands  have  been 
described  by  Thomson,0  Andersson,6  and  others,  but  according  to 
Andersson’s  interpretation  these  “ stone  rivers,”  which  are  now 
streams  of  angular  blocks  of  rock,  were  formerly  composed  of  fine 
mud,  with  the  blocks  of  rock  buoyed  up  and  carried  along  by  the 
viscous  flow  of  the  mud.  The  movement  has  now  ceased,  and  much 
of  the  fine  material  has  been  removed  by  running  water. 

The  closest  analogy  to  the  rock  glaciers  seems  to  be  found  in  the 
“ rock  streams”  of  the  San  Juan  Mountains  of  Colorado,  described 
by  Cross  and  Howe0  in  the  Silverton  folio  and  more  recently  by 
Howe 3 in  a separate  publication.  Both  are  composed  of  angular 

a Thomson,  Wyville,  The  Atlantic,  p.  245. 

b Andersson,  J.  G.,  Solifluction,  a component  of  subaerial  denudation  : Jour.  Geology,  vol. 
14,  1906,  pp.  91-112. 

c Cross,  Whitman,  and  Howe,  Ernest,  Silverton  folio  (No.  120),  Geol.  Atlas  TT.  S.,  U.  S. 
Geol.  Survey,  1905,  p.  25. 

d Howe,  Ernest,  Landslides  in  the  San  Juan  Mountains,  Colorado  : I'rof.  Paper  U.  S. 
Geol.  Survey  No.  67.  1909. 


SEDIMENTARY  ROCKS. 


55 


talus  from  high  mountains,  and  the  similarities  of  appearance  and 
surface  configuration  are  striking.  The  San  Juan  flows  have  been 
referred  to  in  a textbook  a as  “ talus  glaciers,”  and  the  authors  are  of 
the  opinion  that  in  many  cases  snow  and  ice  have  had  some  part  in 
their  development.  Cross  and  Howe  formerly  believed  that  the  posi- 
tion and  form  of  the  rock  streams  were  due  to  glacial  transportation, 
but  the  absence  of  ice  and  some  other  considerations  led  them  to 
the  opinion  which  they  now  hold,  that  the  rock  streams  were 
formed  by  landslides  which  came  down  a with  a sudden  violent  rush 
that  ended  as  quickly  as  it  started.”  Up  to  the  present  time  no  oppor- 
tunity has  offered  to  prove  conclusively  by  a series  of  observations 
extending  over  a considerable  period  of  time  that  these  rock  glaciers 
are  in  motion  or  to  determine  their  rate  of  movement.  There  are, 
however,  a number  of  significant  facts  which  seem  to  make  this  con- 
clusion necessary. 

Although  on  account  of  climatic  conditions  most  of  the  cirques  in 
which  the  rock  glaciers  head  are  unable  to  support  true  glaciers,  they 
are  on  the  border  line  of  glacial  conditions,  and  although  the  snows 
may  all  melt  away  on  the  surface  during  the  summer  the  ground 
remains  permanently  frozen  a short  distance  below  the  surface  and 
ice  in  the  interstitial  openings  of  a talus  mass  may  remain  unmelted 
indefinitely.  Furthermore,  a few  of  the  rock  glaciers  have  true 
glaciers  at  their  heads  which  extend  downward  as  far  as  climatic 
conditions  are  favorable  and  are  continued  below  by  rock  glaciers 
whose  ice  is  protected  from  the  sun  by  the  heavy  coating  of  debris, 
and  into  such  rock  glaciers  it  is  probable  that  a tapering  tongue  of 
true  glacial  ice  extends  down  a considerable  distance.  But  this 
glacial  ice  is  not  necessary  to  their  movement,  as  is  shown  by  those 
rock  glaciers  which  are  unconnected  with  true  glaciers.  In  addition 
to  the  favorable  climatic  conditions,  the  exceptionally  perfect  develop- 
ment of  these  features  in  the  Nizina  district  is  due  to  the  rugged 
character  of  the  mountains,  with  cirques  having  steep  heads  and 
sides,  and  to  unusually  favorable  conditions  for  rapid  rock  weather- 
ing and  talus  accumulation. 

The  history  of  the  rock  glaciers  of  this  district  is  considered  to 
have  been  as  follows: 

As  the  ice  of  the  last  great  epoch  of  glaciation  began  to  retreat 
and  its  area  to  contract,  the  head  and  side  walls  of  many  of  the 
cirques,  steepened  by  glacial  undercutting  and  by  bergschrund  sap- 
ping, were  exposed  to  the  rapid  weathering  characteristic  of  bare 
rock  surfaces  in  the  high  altitudes  of  this  region.  In  many  of 
the  cirques  the  rock  waste  streamed  down  from  the  cliffs  upon  the 
glacier  below  and  was  gradually  carried  away  by  the  ice  and  con- 
centrated at  its  lower  edge.  Here  in  the  usual  order  of  events  it 


Chamberlin,  T.  C.,  and  Salisbury,  It.  D.,  Geology,  vol.  1,  1904,  p.  220. 


56 


THE  NIZINA  DISTRICT,  ALASKA. 


would  have  been  deposited  as  a terminal  moraine,  though  differing 
in  character  from  the  common  forms  of  terminal  moraine  in  the 
preponderance  of  angular,  talus-like  material  and  in  the  propor- 
tionately smaller  amount  of  mud  and  rock  flour  which  form  so  im- 
portant a part  of  the  moraines  of  active  glaciers.  Here  the  small, 
fast-dying  glaciers  were  eroding  but  little  and  were  almost  over- 
whelmed by  the  debris  supplied  them  from  the  cliffs  above.  Into 
the  debris  toward  the  lower  edge  of  the  glacier  the  waters  from 
melting  ice  and  snow  and  from  rains  sank  and  froze  and  gradually 
filled  the  interstices  up  to  a point  below  the  surface  where  melting 
equaled  freezing.  In  these  ice-cemented  masses  a sort  of  glacial 
movement  was  started.  As  the  climate  became  still  milder,  in  many 
cirques  the  winter  snows  all  melted  away  during  the  summer,  so  that 
conditions  for  ordinary  glacial  activity  no  longer  existed,  but  the 
bodies  of  talus  which  reached  the  cirque  floors  became  filled  with 
interstitial  ice  and  the  consequent  movement  of  the  mass  in  a glacier- 
like way  has  continued,  although  no  doubt  all  true  glacial  ice  has 
now  disappeared  from  many  of  the  rock  glaciers.  It  is  certain  that 
much  snow  is  still  carried  down  upon  the  surface  of  the  rock  glaciers 
in  slides  of  snow  and  rock  during  the  winter  and  spring,  and  con- 
siderable quantities  of  it  may  become  covered  by  debris  and  incor- 
porated into  the  rock  glaciers,  but  this  snow  probably  forms  only  a 
small  part  of-  the  total  mass  of  the  flow. 

The  succession  of  events  outlined  seems  to  be  well  established  in 
this  region,  where  are  now  to  be  seen  all  the  stages,  varying  from 
apparently  active  glaciers  with  short  rock  glaciers  below  to  long 
rock  glaciers  in  which  no  glacial  ice  is  seen,  in  valleys  where  all  the 
snow  disappears  during  the  summer;  yet  in  these  latter  the  slow 
movement  seems  still  to  be  in  operation,  the  rate  of  movement  in 
each  flow  being  controlled  by  the  supply  of  talus  from  above  and  by 
the  shape  and  grade  of  the  floor  over  which  it  moves.  The  rock  gla- 
ciers are  therefore  the  true  successors  of  real  glaciers. 

The  rock  glacier  which  lies  on  the  west  side  of  McCarthy  Creek, 
three-fourths  of  a mile  above  the  mouth  of  East  Fork  (PI.  VIII), 
though  by  no  means  the  largest  in  size,  offers  a most  instructive 
example  for  study,  as  it  presents  in  a typical  way  many  of  the  char- 
acteristic features  of  all  of  the  flows.  It  heads  in  a glacial  cirque 
in  a mountain  composed  largely  of  porphyry  but  having  many 
inclosed  masses  of  black  shale,  the  peaks  at  the  cirque  head  reaching 
a height  of  6,315  feet.  The  rock  glacier  occupies  the  cirque  floor 
below  an  elevation  of  5,250  feet,  with  talus  slopes  extending  upward 
above  it  for  about  200  feet.  Above  the  talus  the  whole  face  of  the 
mountain  is  of  bare,  rugged  cliffs  of  porphyry  and  shale,  both  of 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  VIII 


ROCK  GLACIER  ON  McCARTHY  CREEK  THREE-FOURTHS  OF  A MILE  ABOVE  MOUTH  OF  EAST 

FORK. 

Showing  the  source  of  supply  in  the  talus  cones  above,  also  the  surface  markings — longitudinal  in  the  upper 
portion,  concentric  below.  See  page  56. 


SEDIMENTARY  ROCKS. 


57 


which  weather  easily,  so  that  the  formation  of  talus  is  unusually 
rapid.  The  elevation  of  the  valley  head  is  not  sufficient  for  the 
maintenance  of  a true  glacier,  and  during  the  summer  practically 
all  of  the  snowfall  disappears.  By  July  4,  the  time  of  observation, 
only  small  snow  banks  remained  in  sheltered  places. 

The  rock  glacier  heads  in  the  talus  cones  which  have  been  built  up 
at  the  base  of  the  steep  rock  cliffs.  These  cones,  although  constantly 
added  to  by  waste  from  the  rapidly  weathering  cliffs  above,  have 
nowhere  been  able  to  attain  large  size,  the  materials  evidently  hav- 
ing moved  on  down  the  valley  as  a rock  glacier  as  fast  as  they  were 
supplied  from  above.  From  the  base  of  each  of  the  more  vigorous 
talus  cones  a smooth  ridge  extends  down  the  rock  glacier,  seeming 
to  show  that  the  forward  movement  has  on  the  whole  been  uniform 
and  continuous.  Parallel  longitudinal  ridges  of  this  kind  charac- 
terize the  surface  of  the  upper  three-fourths  of  the  flow.  The  cirque 
basin  above  an  elevation  of  4,000  feet  is  a hanging  valley,  but  below 
this  level  it  joins  the  broad  U-shaped  valley  of  McCarthy  Creek 
with  an  abrupt  change  of  gradient.  As  it  passes  over  the  lip  of  the 
hanging  cirque  the  rock  glacier  cascades  steeply  down  the  valley 
side,  and  on  reaching  the  gentler  slope  below,  being  no  longer  con- 
fined by  restricting  valley  walls,  it  spreads  out  in  a great  lobe  along 
the  valley  bottom.  In  this  lower  lobe  the  longitudinal  surface  mark- 
ings dwindle  out  and  disappear,  giving  place  to  a set  of  beautifully 
developed  concentric  wrinkles  which  parallel  the  borders  of  the 
lobe  (PI.  IX,  B ).  The  origin  of  these  wrinkles  is  not  clear,  but 
they  strongly  suggest  rings  of  growth  and  may  represent  the  amount 
of  annual  movement  of  the  rock  glacier. 

At  its  foot  the  flow  has  pushed  across  the  valley  bottom  to  the 
base  of  the  east  valley  wall,  thus  indicating  clearly  by  its  position 
that  it  was  formed  after  the  retreat  of  the  McCarthy  Creek  Glacier 
beyond  this  point.  The  creek  has  been  crowded  to  the  east  and  occu- 
pies a narrow  channel  between  the  foot  of  the  rock  glacier  and  the 
rock  valley  wall.  The  foot  of  the  flow  is  being  rapidly  cut  away  by 
the  stream  and  in  places  shows  a face  75  to  100  feet  high  in  which 
the  slope  is  about  35°,  or  the  angle  of  rest  for  the  material.  The 
creek,  although  of  large  volume  and  steep  gradient,  has  been  unable 
to  do  more  than  keep  its  channel  open  along  the  foot  of  the  rock 
glacier,  and  it  seems  evident  that  the  flow  is  moving  forward  as  fast 
as  the  stream  can  cut  it  back. 

Another  rock  glacier  which  heads  in  the  same  porphyry-shale 
mountain  as  the  one  just  described  flows  in  a northwest  direction  into 
the  valley  of  National  Creek,  a tributary  of  the  Kennicott  (PI.  IX, 
A).  It  is  remarkable  for  the  unusually  strong  development  of  the 


58 


THE  NIZINA  DISTRICT,  ALASKA. 


longitudinal  ridges  in  its  upper  portion,  and  these  ridges  show  well 
their  mode  of  origin  in  the  separate  talus  slopes  on  the  rock  walls 
above. 

The  flow  in  Amazon  Creek,  just  east  of  the  Kennicott  Glacier,  and 
that  in  the  north  head  of  White  Creek  are  notable  for  their  great 
length  as  compared  with  their  width  and  for  the  uniformity  of  their 
slopes  from  one  end  to  the  other.  The  surface  of  the  former  has  a 
slope  of  15°  and  that  of  the  latter  12°. 

The  rock  glacier  which  heads  in  the  limestone  mountain  half  a 
mile  northeast  of  the  Bonanza  mine  and  flows  eastward  shows  at 
its  upper  end  all  of  the  characteristics  typical  of  these  flows,  but 
at  the  mouth  of  the  hanging  valley  in  which  it  lies  it  streams  down 
to  McCarthy  Creek  as  a symmetrical  talus  cone  (PL  X,  A).  If 
the  material  had  come  down  suddenly  as  a landslide,  no  such  per- 
fect talus  cone  would  have  formed,  and  its  presence  indicates  that 
the  material  of  which  it  is  composed  was  supplied  slowly.  Further- 
more, evidence  that  this  rock  glacier  is  still  moving  is  given  by  the 
fact  that  the  talus  is  still  being  supplied  at  the  head  of  the  cone  and 
is  invading  the  patch  of  bushes  on  its  side. 

The  two  large  rock  glaciers,  one  on  the  south  and  one  on  the  north- 
west side  of  Sourdough  Peak,  are  both  of  the  type  which  originates  in 
narrow  cirques  but  spreads  out  into  broad  lobes  below  the  point  where 
the  cirque  walls  restrict  it.  The  glacier  on  the  south  side  of  this 
mountain  is  especially  noteworthy  on  account  of  the  great  expanse 
of  the  flow  below  as  compared  with  the  narrow  limits  of  the  cirque  in 
which  it  originated. 

In  conclusion,  observation  has  led  to  the  belief  that  these  rock 
glaciers  have  moved  and  that  many  of  them  are  still  moving  in  much 
the  same  way  as  glaciers,  and  that,  although  glacial  ice  may  be  and 
doubtless  is  present  in  a few  of  them,  it  is  not  necessary  to  the  move- 
ment, which  may  be  due  altogether  to  ice  in  the  interstices.  Further- 
more, there  is  no  evidence  that  the  flows  came  down  suddenly  as  land- 
slides, but  there  are  strong  reasons  for  believing  that  they  moved 
down  slowly.  The  facts  and  considerations  which  have  led  to  the 
conclusion  that  the  flows  did  not  come  down  suddenly  but  slowly  and 
that  some  of  them  are  now  in  motion  are  noted  below. 

1.  The  remarkable  resemblance  in  position  and  form  of  the  rock 
glaciers  to  true  glaciers  in  the  immediate  vicinity. 

2.  The  direct  connection  and  perfect  gradation  between  true  gla- 
ciers above  and  rock  glaciers  below. 

3.  The  presence  of  interstitial  ice  at  no  great  depth  below  the  sur- 
face in  all  the  rock  glaciers  which  were  dug  into. 

4.  The  longitudinal  ridges  of  the  upper  portions  of  many  of  the 
flows  that  can  be  traced  directly  to  active  talus  slopes. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  448  PLATE  X 


A.  ROCK  GLACIER  IN  A TRIBUTARY  OF  McCARTHY  CREEK  NORTHEAST  OF  BONANZA  MINE. 

At  the  mouth  of  its  hanging  valley  it  breaks  down  into  a great  talus  cone.  See  pages  58,  59. 


B.  DETAIL  OF  SURFACE  OF  ROCK  GLACIER  ON  TRIBUTARY  OF  McCARTHY  CREEK. 

The  rounded  ridges  in  the  foreground  are  the  concentric  ridges  which  characterize  the  lower  portion  of  the  flow. 


SEDIMENTARY  ROCKS. 


59 


5.  Nowhere  have  the  talus  slopes  at  the  cirque  heads  been  able  to 
form  any  considerable  accumulations  upon  the  surface  of  the  rock 
glaciers.  This  seems  to  be  strong  evidence  that  the  talus  has  moved 
down  valley  as  fast  as  it  has  been  supplied. 

6.  Most  of  the  rock  glaciers  have  a steep  slope  at  the  lower  end. 
where  the  gently  sloping  surface  of  the  upper  portion  breaks  down 
at  the  edge  at  an  angle  of  rest  as  steep  as  the  material  will  retain.  On 
this  steep  face  the  rock  fragments  show  bare  surfaces,  while  the  talus 
on  the  surface  above  is  usually  lichen  covered.  This  seems  to  show 
that  the  material  is  moving  forward  fast  enough  to  prevent  erosion 
at  the  lower  end  from  establishing  drainage  lines  on  the  face  of  the 
flow  and  from  reducing  it  to  a low-graded  slope. 

7.  McCarthy  Creek,  a swift  stream  of  large  volume,  which  is  now 
actively  cutting  into  the  lower  edge  of  a rock  glacier  on  its  west  side 
(described  on  pp.  56-57)  that  has  been  in  existence  long  enough  for 
large  spruce  trees  to  grow  upon  its  surface,  has  so  far  been  unable  to 
do  more  than  keep  open  a narrow  channel  along  the  foot  of  the  flow. 
There  is  no  evidence  that  the  rock  glacier  ever  extended  75  feet 
farther  eastward  to  the  rock  bluff  on  the  east  side  of  the  valley.  It 
would  be  surprising  if  this  mass  of  material,  coming  down  with  a 
violent  rush,  should  have  failed  by  just  the  width  of  the  creek  to 
cross  the  valley,  and  if  the  stream,  which  is  now  actively  cutting  into 
the  face  of  the  flow,  should  have  been  unable  to  do  more  than  keep 
its  channel  open.  It  appears  more  probable  that  the  slowly  advanc- 
ing edge  of  the  rock  glacier  had  forced  the  stream  to  its  present  posi- 
tion and  that  the  edge  of  the  flow  is  now  farther  advanced  than  it 
has  ever  been  before. 

8.  There  is  no  evidence  that  large  landslides  have  taken  place  in 
this  region  if  these  flows  are  not  landslides.  None  were  seen  below 
the  miles  of  prominent  cliffs  of  the  area,  though  ordinary  talus  cones 
are  abundant. 

9.  The  rock  glacier  on  McCarthy  Creek,  northeast  of  the  Bonanza 
mine  (PI.  X,  A and  B) , ends  below  in  a well-developed  talus  cone. 
If  the  material  had  come  down  suddenly  as  a landslide,  no  such  per- 
fect talus  cone  would  have  been  formed.  The  presence  of  the  cone 
indicates  that  the  material  was  supplied  slowly,  enabling  the  cone  to 
grow  symmetrically.  The  cone  is  still  growing,  as  can  be  seen  from 
the  way  in  which  the  talus  from  above  is  invading  the  patch  of  bushes 
on  its  face. 

10.  Wherever  two  rock  glaciers  from  adjacent  cirques  join  to  form 
a single  flow  the  point  of  junction  shows  that  the  two  branches  have 
flowed  together  synchronously,  without  any  evidence  that  the  flow 
from  one  branch  has  come  down  and  overridden  that  from  the  other. 


60 


THE  NIZlNA  DISTRICT,  ALASKA. 

IGNEOUS  ROCKS. 

TRIASSIC  OR  PRE-TRIASSIC. 

NIKOLAI  GREENSTONE. 

CHARACTER  OF  THE  FORMATION. 

The  Nikolai  greenstone  resembles  a sedimentary  formation  in  its 
structural  features.  It  is  made  up  of  flows  of  basaltic  lava  that  suc- 
ceed one  another  like  beds  laid  down  in  water.  The  beds  or  flows 
are  usually  of  considerable  thickness,  measured  in  tens  of  feet  rather 
than  in  single  foot  units,  and  the  bedded  appearance  is  more  evident 
when  a large  mass  of  the  greenstone  is  seen  from  a distance  great 
enough  to  give  a comprehensive  view  of  its  larger  features. 

The  color  of  the  weathered  surface  is  grayish  green,  but  in  places 
it  has  a reddish  hue.  A fresh  surface  is  dark  olive  or  grayish  green. 
In  texture  it  varies  from  a dense,  rough,  fine-grained  rock  in  which 
individual  crystals  can  not  be  distinguished  to  a medium-grained 
porphyritic  rock.  Many  of  the  flows  are  amygdaloidal  and  have  a 
spotted  appearance,  due  to  the  cavity  fillings.  Some  of  the  spots  or 
amygdules  are  light  gray  or  almost  white,  like  quartz  or  calcite; 
others  are  dark  green  or  gray.  Quartz  is  present  but  is  not  so  fre- 
quently seen  filling  cavities  as  calcite,  yet  these  two  minerals  are  not 
the  only  ones  that  produce  light-colored  amygdules.  Amygdaloidal 
greenstone  bowlders  in  Chititu  Creek  contain  large  spherulitic  aggre- 
gates of  white  crystals,  believed  to  be  thomsonite.  This  rock,  how- 
ever, was  not  seen  in  place.  Dark-colored  amygdules  are  more  com- 
mon than  the  light  ones  and  for  the  most  part  consist  of  chloritic  or 
serpentinous  material.  In  many  places  the  cavities  of  the  lavas  were 
elongated  and  distorted  before  their  present  mineral  filling  was 
introduced,  so  that  the  amygdules  have  peculiar  irregular  forms. 
The  cavities  appear  to  have  been  distributed  throughout  the  flows 
from  top  to  bottom,  for  no  evidence  of  their  being  more  abundant  at 
the  upper  than  at  the  lower  surface  was  observed.  This  is  one  of  the 
reasons  for  suspecting  that  the  lava  was  poured  out  under  water, 
since  the  weight  of  the  water  resting  on  the  surface  of  the  lava  would 
prevent  in  large  measure  the  expansion  of  included  gases  or  steam; 
vet  it  is  admitted  that  no  proof  of  their  submarine  origin  has  been 
discovered.  Interbedded  tuffs  and  shales  were  not  found  in  the 
greenstone.  Frequently  a weathered  surface  of  the  greenstone  is  seen 
where  the  amygdules  have  been  dissolved  out,  leaving  a vesicular 
rock  that  probably  resembles  closely  the  original  lava  flow. 

A newly  broken  surface  of  the  greenstone  would  hardly  lead  one 
to  believe  that  chemical  alteration  had  taken  jflace  to  any  consider- 
able extent,  for  the  rock  appears  to  be  fairly  fresh,  yet  microscopic 
examination  of  the  sections  shows  that  the  alteration  is  advanced 
and  is  general. 


IGNEOUS  ROCKS. 


61 


The  Nikolai  greenstone  is  less  obtrusive  in  its  topographic  expres- 
sion than  either  the  shales  or  the  limestone.  It  forms  steep  slopes 
and  ragged  mountain  tops,  but  the  greenstone  mountains  do  not 
possess  the  sharp,  angular  outlines  of  the  shale  mountains  or  the 
high  wall-like  cliffs  and  the  pointed  spires  of  the  limestone.  Neither 
do  the  lower  greenstone  hills  present  the  smooth,  rounded  contours  of 
the  glaciated  shale  ridges  on  either  side  of  Young  Creek.  The  green- 
stone resists  decay,  but  it  has  numerous  joints  and  fracture  planes 
and  rapidly  breaks  down  under  northern  climatic  conditions.  This 
accounts  for  the  roughness  of  its  ridges,  the  absence  of  smooth  perpen- 
dicular cliffs,  and  the  vast  quantity  of  angular  blocks  below  its  large 
exposures.  Such  blocks  do  not  disintegrate  like  the  shales,  so  that 
greenstone  pebbles  and  bowlders  form  a conspicuous  proportion  of  the 
gravels  and  other  unconsolidated  deposits.  The  greenstone,  like  the 
Chitistone.  limestone,  resisted  strongly  the  distorting  forces  that  are 
so  plainly  expressed  in  the  folding  of  the  McCarthy  shale.  There  is 
even  less  evidence  of  folding  than  in  the  limestone,  but  it  is  apparent 
from  field  observations  that  adjustment  to  pressure  by  faulting  has 
taken  place  extensively. 

PETROGRAPHIC  DESCRIPTION. 

Thin  sections  of  greenstone  studied  with  the  microscope  show  that 
the  rock  is  a typical  diabase  now  much  altered.  The  principal  con- 
stituents are  feldspar  and  colorless  pyroxene.  The  feldspar  is  labra- 
dorite,  occurring  in  lath-shaped  crystals,  and  in  nearly  every  section 
is  more  or  less  altered.  Pyroxene  fills  the  spaces  between  the  feld- 
spars. It  has  been  less  resistant  to  alteration  than  the  feldspar  and 
is  largely  altered  to  a serpentinous  or  chloritic  material.  Accessory 
minerals  are  magnetite  or  ilmenite  and  chalcopyrite ; olivine  and 
iddingsite  are  rare.  The  principal  alteration  minerals  are  serpen- 
tine or  chlorite,  calcite,  and  perhaps  quartz. 

Cavities  in  the  greenstone  were  abundant,  but  have  been  filled  with 
secondary  minerals  such  as  chlorite,  delessite,  calcite,  and,  rarely, 
quartz.  Many  of  the  amygdules  show  an  outer  coating  of  chloritic 
material  and  an  inner  filling  of  radiating  delessite  crystals,  in  some 
sections  associated  with  calcite.  An  opaque  decomposition  product 
is  common. 

DISTRIBUTION. 

The  Nikolai  greenstone  underlies  conformably  the  Chitistone  lime- 
stone and  took  part  in  the  folding  and  faulting  that  the  lower  part 
of  the  limestone  underwent.  Its  distribution,  therefore,  is  related  to 
that  of  the  limestone,  and  most  of  its  outcrops  represented  on  the 
map  lie  in  a narrow  belt  on  the  south  of  the  limestone  belt  that  is 
practically  continuous  and  extends  southeastward  from  the  north- 


62 


THE  NIZINA  DISTRICT,  ALASKA. 


west  corner  of  the  mapped  area  to  the  head  of  Texas  Creek.  This 
belt  has  its  greatest  width  on  Nizina  River.  A branch  extends  east- 
ward up  Chitistone  River  and  then  southeastward  into  the  valley 
of  Glacier  Creek,  a northwestward-flowing  tributary  of  the  Chitistone 
just  beyond  the  eastern  limit  of  the  area  mapped.  The  ridge  be- 
tween Dan  and  Glacier  creeks  is  capped  by  a broad,  flat  syncline 
of  limestone  pitching  gently  northwest,  but  the  base  of  this  ridge 
wherever  it  is  exposed  is  greenstone.  Greenstone  is  exposed  on  both 
sides  of  Chitistone  River.  It  dips  below  the  gravel  floor  of  Nizina 
River  north  of  the  Chitistone  but  rises  to  view  again  on  the  west 
side  and  continues  north  half  a mile  or  more  till  it  is  cut  off  by  a 
fault  beyond  the  limits  of  the  area  mapped. 

In  places  only  a veneer  of  conglomerate  or  shale  of  the  Kennicott 
formation  covers  the  Nikolai  greenstone  and  small  isolated  patches 
of  the  greenstone  appear  where  the  thin  covering  has  been  removed. 
Such  patches  are  seen  about  National  Creek  and  south  of  Nikolai 
Creek.  Two  small  patches  of  greenstone  appear  as  islands  in  the 
gravels  of  Nizina  River,  and  another,  exposed  through  faulting  and 
erosion,  lies  on  the  north  side  of  Copper  Creek. 

THICKNESS. 

It  is  impossible  to  determine  the  thickness  of  the  Nikolai  green- 
stone from  observations  in  the  area  under  consideration,  for  nowhere 
within  this  area  is  the  base  of  the  greenstone  exposed.  Furthermore, 
it  is  not  certain  that  the  base  of  the  greenstone  is  exposed  in  other 
parts  of  Chitina  Valley,  although  it  is  reported  in  the  Chitistone 
River  basin,  and  it  seems  probable  that  certain  tuffaceous  and  shale 
beds  in  the  Kotsina  Valley  may  represent  it. 

The  figures  to  be  given  represent,  therefore,  only  that  part  of  the 
formation  exposed  immediately  below  the  Chitistone  limestone — that 
is,  the  upper  part.  One  of  the  best  localities  for  measurements  is 
on  the  east  side  of  Nizina  River,  just  north  of  Dan  Creek.  The  dip 
of  the  limestone  and  greenstone  is  low  to  the  northeast.  Unless  the 
greenstone  is  reduplicated  by  faulting,  its  thickness  at  this  locality 
is  at  least  4.000  and  possibly  5,000  feet.  The  conditions  for  measure- 
ment in  the  mountain  on  the  west  side  of  Nizina  River  are  less  favor- 
able, but  there  appear  to  be  not  less  than  4,500  feet  of  greenstone 
exposed  there.  About  2,000  feet  are  exposed  on  the  east,  side  of  Mc- 
Carthy Creek  and  3,500  feet  in  the  ridge  on  which  the  Bonanza 
mine  is  situated.  Between  Bonanza  Creek  and  Kennicott  Glacier  a 
thickness  of  over  4,000  feet  of  greenstone  is  exposed.  Faults  are 
difficult  to  locate  in  the  greenstone  unless  some  of  the  other  forma- 
tions are  present  to  give  a clue  to  their  existence,  and  it  is  recognized 
that  faults  of  sufficient  importance  to  impair  the  value  of  the  meas- 
urements given  may  have  escaped  notice.  It  is  highly  probable, 


IGNEOUS  ROCKS. 


63 


however,  that  the  thickness  of  greenstone  in  the  Nizina  district  ap- 
proaches 4,500  feet,  and  there  can  be  little  if  any  doubt  that  it  is 
over  4,000  feet. 

Schrader  and  Spencer  estimated  roughly  the  thickness  of  the 
Nikolai  greenstone  in  the  upper  part  of  Ivotsina  Valley  at  4,000  feet.° 

AGE. 

Inasmuch  as  the  Nikolai  greenstone  is  composed  of  lava  flows  and 
so  far  as  known  does  not  contain  intercalated  fossil-bearing  beds, 
the  determination  of  its  age  depends  on  its  relation  to  the  formations 
with  which  it  is  associated.  The  greenstone  may  perhaps  contain 
intruded  sills  of  rock  similar  in  composition  to  the  flows,  but  for 
the  most  part  it  is  made  up  of  lavas  that  were  poured  out  before  the 
Chitistone  limestone  began  to  be  deposited.  It  can  not  therefore  be 
later  than  Upper  Triassic.  Unfortunately  no  evidence  has  been 
collected  to  fix  a lower  age  limit.  North  of  the  Nizina  district,  in 
the  valley  of  Skolai  Creek  and  about  Skolai  Pass  and  the  head  of 
White  River,  the  massive  upper  Carboniferous  limestone  is  overlain 
by  thin  shale  beds,  tuffs,  and  lava  flows.  These  overlying  beds  are 
believed  to  rest  on  the  limestone  conformably.  The  lava  flows  in- 
crease rapidly  in  amount  as  the  succession  is  followed  upward  until 
they  finally  predominate.  There  is  a possibility  that  the  Nikolai 
greenstone  represents  the  upper  part  of  these  lavas  overlying  the 
Carboniferous  limestone,  in  which  case  their  age  would  be  Triassic. 
Brooks  and  Kindle  have  presented  evidence  to  show  that  Triassic 
sediments  along  the  upper  Yukon  rest  conformably  on  limestone  of 
the  same  age  as  the  limestone  on  White  River.&  There  is  therefore 
some  degree  of  probability  that  a similar  relation  of  Carboniferous 
and  Triassic  formations  of  the  Wrangell  Mountains  may  sometime 
be  established.  A comparison  of  the  Nikolai  greenstone  with  the 
rocks  south  of  Chitina  River  is  of  interest  but  throws  little  light  on 
the  age  of  the  greenstone.  The  rocks  south  of  the  Chitina  are  chiefly 
sediments,  schists,  graywackes,  and  limestones,  all  much  meta- 
morphosed rocks.  Their  age  is  not  known  but  they  are  usually 
referred  to  the  Paleozoic.  The  degree  of  alteration  in  them  is  far 
greater  than  in  the  greenstone,  and  if  this  fact  may  be  used  as  evi- 
dence the  greenstone  is  considerably  younger.  With  our  present 
knowledge  it  is  hardly  possible  to  say  anything  more  definite  con- 
cerning the  age  of  the  greenstone  than  that  it  is  older  than  the 
Chitistone  limestone  and  probably  is  Triassic. 

° Schrader,  F.  C.,  and  Spencer,  A.  C.,  The  geology  and  mineral  resources  of  a portion  of 
the  Copper  River  district,  Alaska:  Special  publication  of  the  U.  S.  Geol.  Survey,  1901, 
p.  42. 

b Brooks,  A.  H.,  and  Kindle,  E.  M.,  Paleozoic  and  associated  rocks  of  the  upper  Yukon, 
Alaska  : Bull.  Geol.  Soc.  America,  vol.  19,  1908,  p.  305. 


64 


THE  NIZINA  DISTRICT,  ALASKA. 


JURASSIC  OR  POST-JURASSIC  IGNEOUS  ROCKS. 

QUARTZ  DIORITE  PORPHYRY  INTRUSIVES. 

LITHOLOGIC  CHARACTER. 

Light-colored  porphyritic  intrusive  rocks  are  abundant  in  the 
Kennicott  formation  and  are  confined  almost  entirely  to  that  for- 
mation, for  it  is  a remarkable  fact  that  intrusives  are  rare  in  the 
Triassic  sediments  and  the  greenstone.  These  intrusive  rocks  occur 
in  the  form  of  laccoliths,  dikes,  and  sills.  They  show  considerable 
differences  in  texture  and  vary  from  fine-grained,  almost  aphanitic 
phases  to  distinctly  granular  phases  in  which  larger  crystals  or 
phenocrysts  of  feldspar  and  quartz  are  included.  The  color,  too, 
varies  from  almost  white  to  creamy  wThite  and  various  shades  of 
gray  and  brown.  Small  phenocrysts  of  quartz  with  perfect  crystal 
outlines  are  common,  but  as  a rule  the  more  abundant  feldspar  crys- 
tals are  less  distinct  owing  to  chemical  alteration  that  has  taken 
place.  It  seems  rather  remarkable  that  the  rock  should  be  so  fine 
grained  as  it  is  in  some  of  the  larger  intrusives  and  that  it  should 
have  had  so  litle  effect  on  the  shales  into  which  it  was  intruded. 

The  porphyries  show  many  stages  of  alteration,  from  intrusions 
that  look  perfectly  fresh  to  those  in  which  the  feldspars  are  almost 
wholly  decomposed  and  the  rock  has  a dull,  lifeless  appearance.  A 
curious  banded  arrangement  of  alteration  products  was  noted  in 
some  of  the  light-colored,  fine-grained  intrusives.  Different  stages 
in  the  advancement  of  alteration  are  indicated  by  concentric  zones  of 
yellowish-brown  and  white  color,  which  show  that  the  chemical 
changes  proceeded  in  an  orderly  way  from  the  surface  toward  the 
center  of  each  joint  block. 

In  many  places  large  masses  of  black  shale  have  been  caught  up  in 
the  body  of  an  intrusive  and  stand  out  in  a most  conspicuous  way 
against  the  lighter-colored  porphyry  background  (PL  XI,  A).  Some 
of  these  intruded  shale  masses  are  half  a mile  in  length  along 
their  outcrops  and  give  the  appearance  of  thin  shale  beds  between 
very  thick  porphyry  sills.  In  general,  however,  the  included  shale 
masses  are  much  smaller. 

The  porphyries  resist  decomposition  but  readily  break  down  into 
slabs  and  angular  fragments  which  give  rise  to  extensive  talus 
slopes,  or  “ rock  slides,”  as  they  are  locally  called.  Such  debris, 
because  of  its  light  color  and  its  resistance  to  decay,  gives  character 
to  slopes  of  loose  material,  and,  although  the  dikes  or  sills  from  which 
it  came  may  form  only  a minor  portion  of  the  rock  mass,  it  almost 
completely  hides  the  presence  of  shale  or  other  kinds  of  rock. 

Dikes  and  sills  are  numerous  but  present  no  unusual  features  fur- 
ther than  that  some  of  the  sills  persist  for  long  distances  and  in 


BULLETIN  443  PLATE  XI 


NORTH  END  OF  PORPHYRY  PEAK,  SHOWING  INCLUSIONS  OF  B.  PORPHYR1TIC  INTRUSIONS  IN  BLACK  SHALE  OF  KENNICOTT 

BLACK  SHALE  IN  PORPHYRY.  FORMATION  ON  McCARTHY  CREEK. 


IGNEOUS  ROCKS. 


65 


places  take  the  form  of  long  overlapping  lenses.  There  is  a marked 
tendency  for  the  intruded  rock  to  follow  bedding  planes  rather  than 
to  cut  across  the  beds,  so  that  the  sills  are  more  numerous  than  dikes. 
Some  of  the  sills  in  the  black  shales  on  the  south  side  of  Copper  Creek 
valley  continue  uninterruptedly  for  several  miles  and  are  such  dis- 
tinct features  that  the  prospectors  have  given  them  numbers,  as  the 
first,  second,  etc.  They  vary  in  thickness  from  a foot  or  two  to  100 
feet  and  give  valuable  aid  in  determining  structure  in  the  shales. 


Figure  4.— Diagram  showing  the  overlapping  of  lenticular  porphyry  sills  in  the  black 
shales  south  of  Copper  Creek.  Some  of  the  lenses  are  10  to  15  feet  thick. 

A good  example  of  the  way  in  which  the  porphyry  dikes  cut  the  black 
shales  is  given  in  Plate  XI,  B.  (Se6  also  fig.  4.) 

PETROGRAPHIC  DESCRIPTION. 

Microscopic  examination  of  thin  sections  of  the  porphyry  intru- 
sives  shows  that  perfectly  fresh  unaltered  specimens  are  hardly  to 
be  found  and  that  alteration  products  are  practically  always  present. 
The  rock  has  a fine-grained  groundmass  consisting  chiefly  of  feld- 
spar more  or  less  altered  and  a little  quartz  in  which  are  phenocrysts 
of  feldspar  and  quartz.  Various  degrees  of  crystallization  appear 
in  the  groundmass,  but  its  perfection  may  be  obscured  by  chemical 
alteration  that  has  taken  place  since  the  magma  consolidated.  One 
or  two  of  the  sections  studied  are  from  specimens  in  which  crystalliza- 
tion had  not  proceeded  far  when  it  was  interrupted  by  cooling  of  the 
intrusive  rock.  These  sections  show  a fine-grained  groundmass, 
almost  isotropic,  filled  with  tiny  forked  skeleton  laths  or  crystals  of 
feldspar.  Most  sections,  however,  show  a more  advanced  degree  of 
crystallisation.  The  feldspar  is  of  the  more  acidic  plagioclase  variety. 
Zonal  phenocrysts  give  an  opportunity  to  determine  that  they  belong 
mostly  to  the  oligoclase-andesine  series.  Ortlioclase  appears  in  a few 
specimens.  Quartz  in  rounded  plates  or  with  embayments  is  not 
uncommon,  but  for  the  most  part  the  outlines  are  sharp  and  angular. 
Brown  mica  is  usually  present,  as  are  also  shreds  and  scales  of  color- 
less mica.  Hornblende  is  the  next  most  common  ferromagnesian 
mineral.  Many  of  the  crystals  are  much  altered,  and  in  some  sections 
the  former  presence  of  hornblende  is  known  only  by  the  decomposi- 
tion products  taking  the  form  of  the  characteristic  hornblende  cross 
section.  Pyroxene  was  found  in  one  specimen.  Most  sections  show 
a black  metallic  mineral  like  magnetite  and  brown  iron-oxide  stain. 


66 


THE  NIZINA  DISTRICT,  ALASKA. 


Alteration  begins  in  the  feldspars  and  results  in  the  production 
of  fine  scales  of  a highly  refractory  mineral,  probably  muscovite, 
that  appear  in  fractures  and  along  some  of  the  zonal  bands  of  the 
phenocrysts.  Calcite  is  a common  secondary  mineral  and  results 
from  the  decomposition  of  hornblende  and  of  feldspar,  yet  it  may 
have  been  introduced  in  part  by  circulating  water.  Calcite  resulting 
from  decomposition  of  hornblende  is  associated  with  iron  oxide. 

DISTRIBUTION. 

Porphyritic  intrusions  are  present  in  the  black  shales  of  the  Ken- 
nicott  formation  in  all  parts  of  the  Nizina  district,  but  they  have 
their  greatest  development  north  of  Nizina  River.  Porphyry  Peak 
and  Sourdough  Peak  are  composed  largely  of  porphyry,  as  is  also 
the  mountain  north  of  Nikolai  Creek.  The  upper  parts  of  all  three 
are  made  up  almost  entirely  of  porphyry  in  which  are  included 
masses  of  black  shale.  These  laccoliths  form  a hard  resisting  cap 
on  the  softer  shale  base  and  doubtless  have  been  an  important  factor 
in  protecting  the  shale  from  erosion.  There  are  no  such  large  por- 
phyry masses  in  the  black  shales  southeast  of  Nizina  River,  but  sills 
and  dikes  are  numerous  in  all  the  shale  mountains  from  Dan  Creek 
to  Young  Creek.  They  appear  to  be  more  numerous  on  Dan  and 
Copper  creeks  and  about  the  head  of  Rex  Creek  than  they  are  far- 
ther south,  but  the  steep,  bare  sides  of  the  mountains  in  the  former 
locality  give  better  opportunities  for  discovering  them  than  the  lower 
timber  and  moss-covered  slopes  of  the  latter.  The  preference  shown 
by  the  intrusives  for  the  black  shales  is  considered  as  evidence  that 
the  molten  rock  was  able  to  force  itself  into  the  black  shales  more 
easily  than  into  the  lower  formations  or  the  upper  part  of  the  Ken- 
nicott  formation.  It  is  remarkable,  when  one  considers  their  num- 
ber in  the  Kennicott  formation,  that  so  few  intrusives  are  present  in 
the  Triassic  sedimentary  formations  and  the  greenstone.  Special 
attention  was  given  to  this  point  during  the  course  of  field  work, 
since  it  was  assumed  that  the  intruding  rocks  must  cut  the  older 
formations  in  order  to  reach  the  overlying  younger  formations  and 
that  traces  of  some  of  the  conduits  through  which  the  melted  rock 
rose  would  be  found.  A few  dikes  were  discovered,  but  they  do  not 
seem  to  bear  any  proper  relation  in  size  and  number  to  the  amount 
of  intruded  matter  in  the  shales,  so  that  one  is  forced  to  conclude  that 
the  intrusives  entered  the  shales  through  some  channel  not  exposed. 

AGE. 

Intrusives  in  the  Kennicott  formation  can  not  be  older  than  the 
rocks  into  which  the}7  are  intruded.  Consequently  they  can  not  be 
older  than  late  Jurassic  or  possibly  early  Cretaceous.  No  evidence 
bearing  on  their  upper  age  limit  was  discovered  in  the  Nizina  district. 
It  is  perhaps  true  that  the  intrusions  did  not  all  take  place  at  one  time, 


STRUCTURE. 


67 


and  there  might  be  cited  as  bearing  on  this  point  the  fact  that  there 
is  considerable  variation  in  the  composition  and  alteration  of  the 
intruded  rocks.  These  two  facts,  however,  are  not  in  themselves 
proof.  Such  evidence  as  the  intersection  of  one  dike  or  sill  by  an- 
other dike  or  sill  was  not  found,  and  it  seems  probable  that  the  quartz 
porphyry  intrusions  belong  to  one  period  of  intrusion. 

Paige  and  Knopf  have  presented  evidence  to  show  that  the  quartz 
diorites  of  the  Talkeetna  Mountains  are  later  than  Middle  Jurassic 
but  younger  than  the  late  Jurassic,  and  state  that  they  are  “ thus 
contemporaneous  in  a general  way  with  that  great  series  of  batho- 
lithic  intrusions  of  late  Mesozoic  age  which  affected  the  entire  Cor- 
dilleran  region  from  the  Straits  of  Magellan  to  the  Seward  Peninsula 
of  northwestern  Alaska.”0  Quartz  diorites  of  equivalent  age  intrude 
Upper  Jurassic  sediments  in  the  Nutzotin  Mountains  northeast  of 
the  Wrangell  Group. & There  is  a strong  presumption  that  the  quartz 
diorite  porphyries  of  the  Nizina  district  are  but  one  manifestation  of 
a disturbance  that  was  widespread  and  of  much  greater  importance 
in  many  other  localities  than  it  was  here. 

STRUCTURE. 

Reference  has  already  been  made  in  the  descriptions  of  the  different 
formations  to  most  of  the  structural  features  of  the  district,  but  for 
the  sake  of  clearness  these  facts  are  here  brought  together  in  one 
section.  Examination  of  the  geologic  map  (PI.  Ill,  in  pocket)  shows 
that  in  a general  way  the  formations  lie  in  zones  extending  in  a 
northwest-southeast  direction.  Two  sections  are  placed  on  the  map 
to  interpret  the  structure  of  these  formations.  They  show  that  the 
prevailing  dip  of  the  formations  below  the  Kennicott  is  toward  the 
northeast  but  that  the  prevailing  dip  of  the  Kennicott  itself  is  toward 
the  southwest,  and,  further,  that  in  consequence  of  the  greater  dis- 
turbances that  have  taken  place  in  the  older  formations  their  general 
dip  is  considerably  greater.  Section  A-A  shows  the  synclinal  struc- 
ture of  the  Nikolai,  Chitistone,  and  McCarthy  formations  along  the 
northern  boundary  of  the  mapped  area  west  of  Nizina  River.  A 
parallel  section  northeast  from  any  point  on  Dan  Creek  to  Chitistone 
River  or  Glacier  Creek  would  have  shown  this  synclinal  structure  but 
with  the  syncline  much  flattened  out,  and  a comparison  of  such  a sec- 
tion with  section  A-A  and  the  map  would  show  that  the  synclinal 
axis  pitches  gently  northwest.  Section  A-A  also  shows  the  uncon- 
formable  relation  of  the  Kennicott  to  the  older  formations,  its  com- 
paratively low  southwesterly  dip,  and  the  fault  that  here  displaces 
the  basal  beds  of  the  Kennicott  and  the  Nikolai  greenstone.  Section 

® Paige,  Sidney,  and  Knopf,  Adolph,  Geologic  reconnaissance  in  the  Matanuska  and 
Talkeetna  basins,  Alaska  : Bull.  U.  S.  Geol.  Survey  No.  327,  1907,  p.  20. 

bMoffit,  Fred  H.,  and  Knopf,  Adolph,  Mineral  resources  of  the  Nabesna- White  district, 
Alaska  : Bull.  U.  S.  Geol.  Survey  No.  417,  1910. 


68 


THE  NIZINA  DISTRICT,  ALASKA. 


B-B  shows  the  Kennicott  formation  dipping*  gently  to  the  southwest 
in  broad  open  folds.  The  southwest  dip  is  small  but  is  sufficient  to 
bring  the  interbedded  shale  and  sandstone  forming  the  upper  part 
of  the  Kennicott  formation  well  down  on  the  slope  of  the  mountains 
south  of  Young  Creek,  although  these  beds  appear  only  on  the  tops 
of  the  high  mountains  south  of  Copper  Creek  and  about  the  head  of 
Rex  Creek.  At  the  northeastern  end  of  this  section  the  greenstone 
and  the  limestone  lie  almost  horizontally,  but  a displacement  has 
taken  place  by  which  the  limestone  is  brought  into  contact  with  the 
black  shale  of  the  Kennicott  formation,  and  it  appears  that  near  the 
fault  plane  the  limestone  dips  to  the  southwest  or  toAvard  the  fault. 

Faulting  is  of  common  occurrence  in  the  Nizina  district,  but  with 
the  exception  of  the  fault  shown  on  the  two  sections  most  of  the  dis- 
placements are  comparatively  small  in  amount.  The  great  fault  just 
referred  to  is  a strike  fault — that  is,  its  trend  is  the  same  as  the  pre- 
vailing strike  of  the  formations  and  it  extends  from  Copper  Creek 
northwestward  to  McCarthy  Creek.  From  work  done  in  previous 
years  it  is  known  that  this  great  fault  continues  westAvard  beyond  the 
Kennicott  Glacier,  but  its  course  there  has  not  been  traced. 

Good  opportunities  for  studying  the  fault  were  found  at  tAvo  locali- 
ties, one  on  the  South  Fork  of  Nikolai  Creek  and  the  other  on  Dan 
and  Copper  creeks.  The  north  slope  of  the  South  Fork  of  Nikolai 
Creek  is  a dip  slope  formed  by  a thin  veneer  of  basal  Kennicott 
beds  resting  on  greenstone.  (See  section  A— A,  PL  III.)  The  south 
slope  shoAvs  the  basal  Kennicott  in  the  creek  with  a narrow  belt  of 
greenstone  above  it  and  above  the  greenstone  a great  thickness  of 
Kennicott  dipping  to  the  soutlrwest.  The  Kennicott  and  Nikolai 
formations  in  this  locality  were  displaced  by  a fault  in  such  a way 
that  the  rocks  on  the  south  side  now  have  a relatively  higher  position 
than  those  on  the  north  side.  The  fault  dips  high  to  the  northeast 
and  the  displacement  is  about  800  feet.  Very  different  conditions 
prevail  on  Dan  and  Copper  creeks.  Section  B-B,  Plate  III,  shoAvs 
that  the  north  slope  of  Dan  Creek  is  formed  of  Nikolai  greenstone  and 
Chitistone  limestone  lying  in  a practically  horizontal  position.  This 
condition  does  not  hold  on  the  south  side;  instead  a great  block  of 
limestone  abuts  against  black  Kennicott  shales  and  forms  the  point 
of  the  obtuse  angle  between  Dan  and  Copper  creeks.  In  this  locality 
the  displacement  involves  a raising  of  the  north  side  relatively  to 
the  south  side,  exactly  the  reverse  condition  from  that  in  the  Nikolai 
Creek  locality.  This  fault  dips  about  60°  NE.  on  Dan  Creek  and, 
although  complicated  by  minor  cross  faults,  has  a displacement  that 
seems  to  be  nearly  or  quite  the  thickness  of  the  Chitistone  limestone. 

The  same  relative  movement  as  that  on  Dan  Creek  took  place  on 
the  tAvo  sides  of  the  fault  on  the  Avest  side  of  Kennicott  Glacier — that 
is,  the  formations  on  the  north  side  were  raised — yet  no  direct  evidence 


STRUCTURE.  69 

was  discovered  to  prove  the  existence  of  the  fault  between  the  glacier 
and  McCarthy  Creek. 

Faults  of  this  kind  in  which  the  relative  movements  of  the  two 
walls  are  opposite  in  direction  at  two  different  localities  are  known 
elsewhere,  yet,  inasmuch  as  the  gravels  of  Nizina  River  prevent  the 
demonstration  that  the  Dan  Creek  fault  is  continuous  with  that  of 
Nikolai  Creek,  it  should  be  stated  that  the  conditions  described  might 
result  from  the  dropping  of  a block  between  two  parallel  faults,  in 
which  case  we  should  be  dealing  not  with  one  but  rather  with  two 
faults.  No  evidence  was  seen  in  the  field  to  raise  a suspicion  that 
two  closely  spaced  faults  occur  here.  A perpendicular  fault  almost 
parallel  with  the  Dan  Creek  fault  traverses  the  Young  Creek  valley, 
and  a third,  whose  strike  is  more  nearly  east  and  west,  crosses  Nizina 
River  a short  distance  north  of  the  limits  of  the  area  mapped.  The 
Young  Creek  fault  is  probably  of  the  same  order  of  magnitude  as 
that  of  Dan  Creek  but  is  more  difficult  to  study,  since  only  one  for- 
mation is  concerned  in  the  localities  where  it  was  examined.  It  has 
a known  horizontal  extension  of  5 or  6 miles  and  the  zone  of  dis- 
turbance is  a wide  one.  These  displacements,  however,  throw  no 
light  on  the  problems  of  Dan  and  Nikolai  creeks. 

The  three  faults  just  mentioned  are  the  most  prominent  ones  of  the 
Nizina  district,  but  they  are  not  the  only  ones.  There  is  evidence  in 
many  places  of  movement  of  the  greenstone  and  limestone  formations 
along  their  plane  of  contact,  but  measurements  of  displacement  under 
such  conditions  are  difficult.  Undoubtedly  faults  are  present  in 
many  places  where  they  have  not  been  recognized,  for  it  is  only 
under  favorable  conditions  that  they  are  discovered.  Such  condi- 
tions are  provided  by  the  limestone-greenstone  contact.  The  char- 
acter and  frequency  of  faulting  are  shown  on  the  geologic  map  by  the 
contact  north  of  Dan  Creek.  Displacements  of  the  kind  occurring 
there  are  difficult  to  recognize  and  to  trace  where  only  one  of  the 
formations  is  present.  Most  of  the  observed  minor  faults  make 
obtuse  angles  approaching  90°  with  the  major  strike  faults  and  are 
vertical  or  nearly  so.  They  are  present  in  many  places  and  are 
commonly  of  small  displacement  in  comparison  with  the  strike  faults 
even  when  of  considerable  horizontal  extension.  The  shear  zone  of 
the  Bonanza  ore  body  is  of  this  class.  It  was  traced  in  a direction 
N.  30°  E.  from  the  mine  for  a distance  of  1 mile,  but  the  displacement 
at  the  limestone-greenstone  contact  is  only  2 feet.  A parallel  fault 
on  the  east  side  of  McCarthy  Creek  has  a displacement  of  over  500 
feet.  The  numerous  faults  north  of  Dan  Creek  are  vertical  or  nearly 
so  and  have  displacements  ranging  from  10  or  15  feet  to  several 
hundred  feet.  Minor  strike  faults  were  also  noted,  but  since  they 
do  not  cut  bedding  or  formation  boundaries  they  are  apt  to  be  un- 
discovered, as  are  also  faults  of  low  dip,  such  as  the  horizontal  frac- 


70 


THE  NIZINA  DISTRICT,  ALASKA. 

ture  planes  of  the  Bonanza  mine,  along  which  slight  movement  has 
taken  place. 

In  summarizing  what  has  been  said  about  faulting  attention  is 
directed  to  the  fact  that  in  a broad  way  the  faults  may  be  divided 
into  two  classes,  those  parallel  to  the  prevailing  strike  of  the  forma- 
tions and  those  that  are  approximately  perpendicular  to  it.  These 
may  be  referred  to  as  strike  faults  and  dip  faults,  for  they  are 
vertical  or  approximately  so,  and  their  strikes  correspond  in  a meas- 
ure with  the  direction  of  strike  and  dip  of  the  formations. 

The  principal  strike  faults  have  given  rise  to  great  displacement 
of  the  rocks  cut  by  them  and  persist  for  long  distances  horizontally. 
The  dip  faults  are  more  numerous  but  the  displacements  are  smaller. 
The  effects  of  these  faults  on  the  rocks  may  be  compared  to  the 
fracturing  of  the  ice  in  a glacier.  Blocks  were  formed  which  had  to 
adjust  themselves  to  surrounding  conditions;  some  of  them  moved 
up,  some  down,  as  will  be  seen  by  examining  the  limestone-greenstone 
contact  north  of  Dan  Creek.  In  this  way  adjustments  of  great 
amount  were  brought  about  by  many  small,  widely  distributed 
displacements. 

AREAL  GEOLOGY. 

The  areal  distribution  of  each  formation  has  been  indicated  in  the 
description  of  the  formation.  It  now  remains  to  bring  these  scat- 
tered facts  together  in  one  brief  statement.  Fully  one-third  of  the 
mapped  area  is  occupied  by  unconsolidated  gravels,  sands,  etc.,  of 
glacial  and  fluvial  origin  (PL  III,  in  pocket).  Two-thirds  of  the 
remainder  is  given  to  the  Kennicott  formation.  Consequently  less 
than  one-fourth  remains  to  the  rocks  older  than  the  Jurassic.  The 
greenstone,  the  limestone,  and  the  Triassic  shales  are  confined  strictly 
to  a belt  along  the  northeastern  side  of  the  area,  but  their  territory 
is  invaded  in  a few  places  by  outliers  of  the  overlying  basal  beds  of 
the  Kennicott  formation.  Triassic  shales  occupy  only  a small  part 
of  the  area  belonging  to  the  older  rocks,  for  the  map  does  not  extend 
far  enough  north  to  include  the  places  of  their  greatest  develop- 
ment. They  are  seen  along  the  boundary  of  the  mapped  area  be- 
tween McCarthy  Creek  and  Nizina  River  and  in  the  vicinity  of 
Copper  Creek.  The  Nikolai  greenstone  and  the  Chitistone  lime- 
stone form  a narrow  belt  that  extends  northwest  from  Pyramid 
Peak  to  Kennicott  Glacier.  Nothing  but  Kennicott  sediments  and 
the  igneous  rocks  intruded  in  them  appears  south  of  the  Triassic 
formations.  They  appear  in  two  principal  areas  on  the  two  sides  of 
Nizina  River  and  are  separated  by  a broad  stretch  of  gravel  deposits. 
Quartz  diorite  porphyries  cut  the  Kennicott  sediments  in  all  parts 
of  the  district  but  find  their  greatest  development  in  the  black 
shales,  particularly  the  shale  area  north  of  Nizina  River.  The  per- 


HISTORICAL  GEOLOGY. 


71 


phyry  sills  of  Copper  Creek  are  conspicuous  because  of  their  per- 
sistence, but  the  intrusives  of  Porphyry  and  Sourdough  peaks  are 
so  much  greater  in  amount  that  they  dominate  in  the  upper  parts 
of  these  mountains. 

It  may  not  be  out  of  place  to  state  here  that  the  four  formations  of 
the  Nizina  region  continue  northwestward  beyond  Kennicott  Glacier 
and  that  their  areal  relations  there  are  practically  the  same  as  on 
the  east  side.  Black  Kennicott  shales  with  numerous  porphyry  in- 
trusives make  up  the  mountains  west  of  Porphyry  Peak  on  the 
opposite  side  of  Kennicott  River,  and  the  greenstone  and  Triassic 
sedimentary  formations  appear  north  of  Fourth  of  July  Pass.  The 
mountain  in  the  middle  of  the  glacier,  known  as  “ The  Peninsula,” 
gives  an  excellent  section  of  the  greenstone  and  the  two  Triassic  for- 
mations. Greenstone  forms  the  southern  point  of  u The  Peninsula.” 
On  it  lies  the  northeastward-dipping  limestone,  which  is  succeeded  in 
turn  by  the  Triassic  shales.  This  locality  is  one  of  a few  in  this 
region  where  the  limestone  has  been  closely  folded  and  much  con- 
torted. 

It  is  known  regarding  the  extension  of  these  formations  toward 
the  southeast  that  the  greenstone  outcrops  on  Canyon  Creek  east  of 
Young  Creek,  and  it  is  probable  that  both  greenstone  and  limestone 
extend  still  farther  eastward  into  the  Chitina  Valley.  Schrader 
traced  the  black  Jurassic  shales,  which  were  at  first  thought  to  be 
Triassic,  as  far  east  as  Canyon  Creek,  but  beyond  that  there  is  no 
information  concerning  them. 

HISTORICAL  GEOLOGY. 

SEDIMENTARY  AND  IGNEOUS  RECORD. 

In  describing  the  formations  of  the  Nizina  district  the  rocks  of 
sedimentary  origin  were  considered  in  one  group  and  those  of  igneous 
origin  in  a second.  This  treatment  by  family  groups  is  not  followed 
in  the  discussion  of  the  historical  geology  of  the  district,  but  rather 
it  is  attempted  to  give  in  the  order  of  their  occurrence  the  geologic 
events  connected  with  the  different  rocks. 

The  first  event  in  the  geologic  history  of  the  district  concerning 
which  we  have  evidence  within  the  district  is  the  outpouring  of  lavas 
that  are  now  known  as  the  Nikolai  greenstone.  This  took  place  pre- 
vious to  the  deposition  of  the  Chitistone  limestone,  and  consequently 
either  in  Upper  Triassic  time  or  in  some  period  preceding  it.  It 
is  not,  probable,  however,  that  the  greenstone  flows  are  older  than 
the  Triassic,  since  the  best  evidence  at  hand  indicates  that  they  are 
later  than  Carboniferous.  The  flows  did  not  take  place  as  a single 
event  but  were  doubtless  continued  through  a considerable  time 
interval.  There  is  some  reason  to  believe  that  they  may  have  been 


72 


THE  NIZINA  DISTRICT,  ALASKA. 


poured  out  under  water,  although  it  is  by  no  means  established  that 
such  is  the  case ; yet,  whether  they  accumulated  in  the  sea  or  whether 
they  accumulated  on  land  and  were  later  carried  below  sea  level  by 
subsidence  of  the  land,  the  beginning  of  deposition  of  Upper  Triassic 
marked  the  complete  cessation  of  volcanic  activity  for  the  time  being. 
Deposition  of  the  Chitistone  limestone  continued  for  a long  interval 
of  time  without  important  changes  in  the  character  of  the  material 
laid  down.  At  first  the  conditions  of  accumulation  were  relatively 
stable  and  the  massive  beds  at  the  base  of  the  Chitistone  were  formed, 
but  later  conditions  changed,  for  the  beds  grew  thinner,  and  finally 
thin  partings  of  shale  began  to  appear.  The  commencement  of  shale 
deposition  marked  the  beginning  of  the  transition  from  the  Chitistone 
limestone  to  the  McCarthy  shale.  As  the  shale  beds  increased  in 
amount  the  limestone  decreased,  till  finally  shale  predominated  and 
limestone  was  no  longer  of  importance  in  the  formation.  All  these 
events  that  concern  the  sedimentary  formations  took  place  before  the 
end  of  the  Triassic  period.  They  terminated  with  an  elevation  of 
the  Triassic  sediments  above  sea  level,  which  was  accompanied  or 
followed  by  deformation  and  folding  of  all  the  sedimentary  beds  and 
the  greenstone.  Erosion  of  the  new  land  surface  began  as  soon  as 
elevation  took  place  and,  unless  part  of  the  historic  record  has  been 
lost  or  overlooked,  continued  throughout  Lower  and  Middle  Jurassic 
time.  During  this  erosion  period  an  enormous  quantity  of  material 
was  removed  from  the  land  and  returned  to  the  sea,  but  what  became 
of  it  is  not  known.  The  beveled  edges  of  the  greenstone,  the  lime- 
stone, and  the  shale  bear  evidence  of  an  areal  extension  of  these 
formations  beyond  the  limits  now  recognized  and  testify  to  the  thou- 
sands of  feet  of  material  carried  away. 

Erosion  was  at  last  interrupted  by  the  advance  of  the  Jurassic 
sea.  This  advance  probably  took  place  from  the  west,  where  it  began 
in  Lower  Jurassic  time,  as  is  known  from  the  presence  of  Lower 
Jurassic  beds  on  Cook  Inlet.  Upper  Jurassic  sea  prevailed  in  the 
Chitina  region  long  enough  to  permit  many  thousand  feet  of  sedi- 
ments to  accumulate.  This  sea  is  supposed  to  have  been  a somewhat 
restricted  one.  The  waters  were  shallow.  Probably  a land  mass 
existed  to  the  south  in  the  region  of  the  present  Chugach  Moun- 
tains and  separated  the  sea  from  the  ocean.  The  sediments  de- 
posited in  the  Jurassic  sea  are  not  all  of  one  kind  and  were  de- 
posited under  varying  conditions.  The  Kennicott  formation  bears 
within  itself  evidence  of  many  and  important  changes  during  the 
time  when  it  was  being  laid  down.  Shore  conditions  are  indicated 
by  the  basal  conglomerate,  but  the  gradual  upward  decrease  in  size 
of  the  pebbles  that  form  the  conglomerate  and  the  transition  from 
conglomerate  or  grit  to  sandstone  and  from  sandstone  to  fine  black 
shales  tell  of  a progressive  change  in  conditions  that  is  difficult 


HISTORICAL  GEOLOGY. 


Y3 


to  interpret,  for  it  may  have  been  caused  in  various  ways.  The 
great  thickness  of  fine  black  shale,  however,  is  evidence  of  long- 
continued  stability  in  the  source  of  supply  and  the  manner  of 
deposition  of  the  materials  composing  them.  Stability  at  last  gave 
place  to  instability,  and  another  great  thickness  of  interbedded 
shales  and  sandstones  followed  the  black  shales  till  the  last  known 
event  of  Upper  Jurassic  deposition  took  place  and  the  massive  upper 
conglomerate  was  laid  down.  Deformation,  elevation  above  sea  level, 
and  intrusion  by  quartz  diorite  porphyry  are  the  next  events  re- 
corded in  the  rocks  of  the  mapped  area,  and  they  lead  up  nearly  to  the 
beginning  of  development  of  the  present  topography.  Yet  there  is 
reason  for  assuming  that  the  Kennicott  formation  does  not  repre- 
sent the  latest  rocks  of  the  Nizina  district  and  that  other  younger 
sedimentary  and  igneous  rocks  may  have  once  been  present  but  are 
now  entirely  removed.  This  assumption  is  based  on  the  presence  of 
coal-bearing  beds  and  still  younger  lava  flows  in  the  vicinity  of 
Fourth  of  July  Creek,  west  of  Kennicott  Glacier,  and  on  the  head  of 
Chitistone  River.  Neither  of  these  localities  has  been  studied  in 
detail.  The  coal  of  Fourth  of  July  Creek  is  confined  to  a small 
area.  It  lies  horizontally,  is  associated  with  black  carbonaceous 
shale,  and  is  overlain  by  arkose  sandstone  and  an  andesitic  lava 
flow.  Its  relation  to  the  great  fault  that  cuts  the  Kennicott  and  older 
formations  is  such  as  to  leave  little  doubt  that  it  was  deposited 
after  faulting  took  place,  and  it  is  provisionally  referred  to  the 
Tertiary.  Coals  associated  with  shales  and  sandstones  and  overlain 
by  lava  flows  are  exposed  on  Chitistone  River.  These  beds  also  are 
referred  to  the  Tertiary.  The  presence  of  these  younger  rocks  in  the 
immediate  vicinity  makes  it  appear  highly  probable  that  they  may 
have  extended  into  the  region  under  consideration,  since  it  is  diffi- 
cult to  understand  how  they  could  have  been  deposited  where  they 
now  appear  without  being  much  more  widespread  than  they  are. 
A coal-bearing  formation  consisting  predominantly  of  coarse  arkose 
and  showing  no  evidence  of  marine  conditions,  but  included  between 
marine  Tertiary  formations,  reaches  a thickness  of  more  than  2,000 
feet  in  the  Controller  Bay  region.® 

More  than  3,000  feet  of  fresh-water  coal-bearing  Tertiary  sedi- 
ments are  exposed  in  the  Matanuska  region.* * 6 

These  sediments  comprise  “ a series  of  sandstones,  shales,  arkose, 
numerous  coal  seams,  and  a large  volume  of  conglomerate.”  The 
Gakona  formation  of  the  Copper  River  basin  c is  a coal-bearing  for- 

® Martin,  G.  C.,  Geology  and  mineral  resources  of  the  Controller  Bay  region,  Alaska  : 

Bull.  U.  S.  Geol.  Survey  No.  335,  1908,  p.  31. 

6 Paige,  Sidney,  and  Knopf,  Adolph,  Geologic  reconnaissance  in  the  Matanuska  and  Tal- 
keetna  basins,  Alaska  : Bull.  U.  S.  Geol.  Survey  No.  327,  1907,  p.  27. 

c Mendenhall,  Walter  C.,  Geology  of  the  central  Copper  River  region  : Prof.  Paper  U.  S. 
Geol.  Survey  No.  41,  1905,  p.  52. 


74 


THE  NIZINA  DISTRICT,  ALASKA. 


mation  of  fresh-water  origin.  It  reaches  a thickness  estimated  to  be 
not  less  .than  2,000  feet  and  includes  500  feet  of  conglomerate,  together 
with  shale,  gravel,  sand,  and  lignite  beds.  Other  areas  of  supposedly 
Tertiary  sediments  appear  in  the  Copper  River  valley,  but  very  little 
is  known  about  them.  If  the  coal-bearing  rocks  occurring  just  north 
of  the  Nizina  district  are  of  Tertiary  age,  it  is  a reasonable  presump- 
tion in  the  absence  of  definite  proof  that  they,  like  the  coal-bearing 
Tertiary  formations  of  the  Matanuska  and  Copper  River  basins,  are 
of  fresh-water  origin,  and  that  therefore  there  is  no  necessity  for 
assuming  a submergence  of  the  region  below  sea  level  after  the  Ken- 
nicott  formation  was  deposited.  The  element  of  doubt  in  this  pre- 
sumption lies  in  the  uncertainty  concerning  the  age  of  the  coal,  for 
it  is  known  that  the  Upper  Jurassic  formations  as  well  as  the  Tertiary 
formations  of  the  Matanuska  region  carry  coal. 

PHYSIOGRAPHIC  RECORD. 

There  is  good  evidence  in  many  parts  of  Alaska  to  show  that  at 
the  time  when  the  Tertiary  coal  formations  were  deposited  the  land 
had  a much  lower  relief  than  it  has  to-day.  The  present  mountain 
ranges,  although  perhaps  distinctly  outlined,  had  not  yet  reached 
their  full  development.  The  coal  formations  were  laid  down  in 
depressions  of  a land  surface  that  must  have  lacked  in  large  measure 
the  rugged  character  that  we  now  see.  Probably  this  land  surface 
presented  many  of  the  features  of  the  present  Copper  River  or 
Yukon  valleys  in  their  broader  parts.  Such  appear  to  have  been 
the  conditions  when  the  forces  that  resulted  in  the  uplifting  produc- 
tion of  the  present  Chugach  Mountains  and  the  Alaska  Range  began 
to  be  felt.  These  forces  doubtless  acted  slowly,  but  they  acted  for  a 
long  period  of  time,  and  they  may  be  in  operation  yet.  They  brought 
about  the  uplift  of  the  mountain  areas  and  made  it  possible  for  the 
agents  of  erosion  to  initiate  the  work  of  forming  the  present  moun- 
tain and  valley  features.  They  wTere  accompanied  by  or  were  the 
cause  of  the  extrusion  of  a great  volume  of  lava  that  has  continued 
almost  to  the  present  day  and  is  the  most  characteristic  feature  of  the 
Wrangell  Mountains,  the  feature  that  distinguishes  them  from  the 
Chugach  Mountains  on  the  south  and  the  Alaska  Range  on  the  north. 

Chitina  Valley  is  a very  old  topographic  feature  and  was  formed 
bv  a stream  that  probably  had  an  outlet  by  way  of  the  upper  Copper 
River  valley  either  into  the  drainage  basin  of  Cook  Inlet  or  possibly 
into  the  Yukon  Valley.  Its  axis  coincides  with  the  boundary  line 
between  the  older  metamorphic  rocks  of  the  Chugach  Mountains  and 
the  younger,  less-altered  rocks  on  the  north  side  of  the  valley.  This 
boundary  in  part  marks  an  unconformity  of  deposition  and  possibly 
also  one  of  faulting,  but  in  either  case  it  appears  to  have  been  a 


ECONOMIC  GEOLOGY. 


75 


determining  factor  in  locating  the  position  of  the  valley.  The  valleys 
of  Nizina  River  and  the  other  streams  of  the  Nizina  district,  like 
the  Chitina  Valley,  originally  represented  the  work  of  streams  alone 
and  were  the  result  of  normal  stream  erosion,  but  they  have  been 
profoundly  modified  by  the  action  of  glacial  ice.  This  modification 
is  represented  chiefly  by  changes  in  valley  forms  due  to  straightening 
of  the  sides,  alterations  in  the  form  of  cross  section,  and  lowering  of 
the  valley  floors,  together  with  changes  brought  about  by  the  deposi- 
tion of  unconsolidated  glacial  materials.  These  modifications  having 
already  been  described  in  the  section  on  glaciation,  it  is  unnecessary 
to  repeat  their  description  here.  It  is  only  necessary  to  say  that  the 
most  conspicuous  topographic  features  we  see  to-day  owe  their 
present  appearance  to  recent  glaciation,  yet  that  subsequent  stream 
cutting  and  rapid  subaerial  erosion  due  to  the  subarctic  conditions 
have  begun  to  modify  the  land  forms  left  by  the  retreating  ice. 
These  later  features  are  seen  in  the  rock- walled  canyons  on  the  lower 
courses  of  all  the  streams,  the  deep  gulches  such  as  cut  the  Kennicott 
formation  on  White  and  Young  creeks,  and  the  great  accumulations 
of  loose  material  in  the  form  of  talus. 

ECONOMIC  GEOLOGY. 

HISTORY. 

The  history  of  mining  in  the  Chitina  Valley  begins  with  the  rush 
of  prospectors  to  Valdez  in  1898.  These  men  were  influenced  by  the 
gold  discoveries  in  the  Yukon  Basin  during  the  preceding  two  years 
and  came  to  Valdez  in  the  hope  of  finding  an  easier  route  to  the 
Yukon  or  new  placers  in  the  Copper  River  valley.  Reports  of  cop- 
per on  Copper  River  had  circulated  since  the  time  of  the  Russians, 
who  found  in  the  hands  of  natives  copper  that  probably  came  from 
the  Nizina  district,  yet  a majority  of  the  prospectors  were  in  search 
of  gold,  not  copper.  A few,  however,  turned  their  attention  to  cop- 
per and  crossed  from  Valdez  to  the  Wrangell  Mountains,  where  their 
efforts  received  encouragement.  In  the  following  year  (1899)  the 
search  for  valuable  minerals  was  resumed  and  prospecting  parties 
ascended  Chitina  Valley  as  far  as  the  Nizina  district.  It  is  doubtful 
if  they  attempted  to  go  farther  east  in  the  main  valley,  and  for  that 
matter  there  has  been  little  effort  to  prospect  the  upper  Chitina 
region  in  the  years  since  then.  The  Nikolai  copper  lode  was  shown 
to  a party  of  white  men  by  a native  sent  for  this  purpose  by  Chief 
Nikolai,  of  Taral,  in  July,  1899.  Nikolai’s  house  was  at  the  mouth  of 
Dan  Creek,  and  the  ore  body  was  doubtless  discovered  by  the  natives 
on  some  of  their  hunting  expeditions.  It  is  usually  difficult  to  recon- 
cile the  statements  of  different  persons  concerning  the  early  events 
connected  with  the  history  of  a new  country,  and  the  Nizina  district  is 


76 


the  nizika  district,  Alaska. 


no  exception  to  the  rule.  It  is  said  that  gold  was  discovered  on  both 
Dan  and  Young  creeks  at  about  this  time,  but  either  the  quantity 
found  was  small  or  the  difficulties  met  prevented  any  immediate  steps 
toward  developing  the  property. 

Work  was  begun  on  the  Nikolai  mine  in  1900  for  the  purpose  of 
securing  a patent  to  the  claim.  Some  of  the  men  who  were  interested 
in  the  property  devoted  part  of  their  time  to  further  prospecting,  and 
in  this  way  the  large  body  of  chalcocite  named  the  Bonanza  ore  body 
was  discovered  about  the  end  of  July  or  the  first  of  August  (1900) 
by  C.  L.  Warner  and  Jack  Smith.  It  was  discovered  independently 
a short  time  later  by  Spencer,  of  the  United  States  Geological  Sur- 
vey, who  was  engaged  in  mapping  the  contact  of  the  Nikolai  green- 
stone and  the  Chitistone  limestone.  Up  to  this  time  interest  in  gold 
placers  had  been  secondary  to  that  in  copper  prospects,  but  the  pres- 
ence of  gold  on  Dan  Creek  was  not  forgotten,  and  in  1901  the  creek 
was  staked  by  C.  L.  Warner  and  D.  L.  Kain  for  themselves  and  others. 
Mr.  Kain  was  known  to  his  companion  as  “Dan,”  and  they  named  the 
creek  after  him. 

The  first  men  to  find  gold  on  Chititu  Creek  were  Frank  Kernan 
and  Charles  Koppus,  who  came  to  the  creek  in  the  first  part  of  April, 
1902.  They  were  joined  shortly  afterwards  by  two  others,  Messrs. 
Rowland  and  Dimmet,  and  these  men  staked  the  creek  for  themselves 
and  their  partners  on  April  25.  News  of  the  Nizina  strike  quickly 
reached  the  outside,  and  by  July  of  1902  the  stampede  was  under 
way.  A new  town  sprang  up  on  Chititu  Creek  and  was  quickly  pro- 
vided with  all  the  usual  elements  of  a thriving  placer  camp,  but 
there  was  not  enough  placer  ground  to  support  all  comers,  and  most 
of  the  population  soon  vanished.  The  richest  and  most  easily  mined 
gravels  were  largely  worked  out  in  the  first  years  by  pick  and  shovel, 
but  since  that  time  the  claims  on  both  Chititu  and  Dan  creeks  have 
become  more  and  more  consolidated  in  the  hands  of  a few  owners, 
who  are  preparing  to  handle  their  gold-bearing  gravels  on  a larger 
scale  by  more  economical  methods. 

A similar  consolidation  of  ownership  has  taken  place  in  the  case 
of  the  Bonanza  mine,  so  that  now  instead  of  11  principal  ownerships, 
some  of  them  representing  two  or  more  persons,  the  property  is  con- 
trolled by  a single  strong  corporation  capable  of  supplying  the  large 
capital  necessary  to  develop  the  ore  body. 

The  mineral  production  of  the  Chitina  Valley  to  the  present  time 
consists  entirely  of  gold,  which  is  practically  all  from  Chititu  and 
Dan  creeks.  Copper  has  not  been  produced  in  a commercial  way 
because  there  is  no  means  of  getting  it  to  the  coast,  so  that  all  the 
copper  brought  out  is  that  taken  for  samples  and  assays. 


ECONOMIC  GEOLOGY. 


77 


COPPER. 

OCCURRENCE  OF  THE  ORES. 

GENERAL  STATEMENT. 

An  examination  of  the  copper  prospects  of  the  Chitina  Valley  was 
made  by  members  of  the  United  States  Geological  Survey  in  1907, 
and  a report  of  that  work  was  published  in  bulletin  form  later.® 

Since  that  time  there  has  been  considerable  advancement  in  the 
development  of  some  properties  and  a few  discoveries  have  been 
made,  yet  the  results  of  the  work  done  have  thrown  no  light  on  the 
nature  of  the  changes  which  take  place  in  the  ore  bodies  as  distance 
from  the  surface  increases.  This  question,  excepting  that  of  the 
amount  of  ore  present,  is  probably  the  most  important  one  con- 
cerning the  copper  deposits  of  the  region.  A study  of  the  copper 
deposits  on  the  eastern  side  of  the  Wrangell  Mountains * *  & has  shown 
that  copper  occurs  there  under  much  the  same  conditions  as  in  the 
Chitina  Valley  and  has  suggested  some  further  ideas  as  to  the  origin 
of  the  ores.  The  descriptions  and  discussion  that  follow,  then,  are 
based  partly  on  previous  work  but  have  received  such  revision  and 
addition  as  have  been  found  to  be  necessary. 

Copper  ores  in  the  Chitina  Valley  north  of  the  river  occur  in  three 
ways — as  copper  and  copper-iron  sulphides  associated  with  the 
Nikolai  greenstone  and  with  the  Chitistone  limestone;  as  native 
copper  associated  with  the  greenstone ; as  placer  copper  accompanied 
by  native  silver  and  gold.  The  important  copper  minerals  are  chal- 
cocite  or  copper  glance,  bornite,  chalcopyrite,  and  native  copper.  In 
every  copper  prospect  there  is  a small  quantity  of  one  or  more  of  the 
oxidation  products,  such  as  green  malachite  stain,  azurite,  and  less 
frequently  the  red  oxide,  cuprite.  Chalcanthite,  or  blue  copper  sul- 
phate, and  the  black  oxide,  tenorite,  are  rare.  Covellite  is  associated 
with  chalcocite  in  some  localities. 

The  ore  bodies  occur  as  replacements  of  greenstone  or  of  limestone 
or  as  fillings  in  cavities  developed  along  fault  planes,  shear  zones,  or 
joint  planes  in  greenstone  or  limestone.  A few  examples  are  known 
of  ore  bodies  to  which  the  term  “ fissure  vein  ” might  be  applied  in 
its  popular  sense,  but  by  far  the  greater  number  of  the  copper  de- 
posits are  aggregates  of  copper  minerals  forming  ore  bodies  of 
irregular  shape  which  are  well  described  by  the  term  “bunch  de- 
posits,” yet  even  the  “ bunch  deposits  ” are  believed  to  owe  their 
existence  to  the  presence  of  faults  or  fractures  that  permitted  the 
circulation  of  copper-bearing  solutions.  Aggregates  of  copper  min- 

" Moffit,  Fred  H.,  and  Maddren,  A.  G.,  Mineral  resources  of  the  Kotsina-Chitina  region, 

Alaska  : Bull.  TJ.  S.  Geol.  Survey  No.  374,  1909. 

6 Moffit,  Fred  H.,  and  Knopf,  Adolph,  Mineral  resources  of  the  Nabesna- White  district, 
Alaska  : Bull.  U.  S.  Geol.  Survey  No.  417,  1910. 


78 


THE  NIZINA  DISTRICT,  ALASKA. 


erals  are  far  more  common  in  the  greenstone  than  in  the  limestone, 
but  the  largest  deposits  that  have  been  discovered  up  to  the  present 
are  in  limestone.  Most  of  the  deposits  in  limestone  are  nea"r  the  base 
of  the  Chitistone  formation,  yet  there  are  a few  notable  exceptions 
to  this  general  rule.  On  the  other  hand,  the  attempt  to  show  that 
deposits  in  the  greenstone  are  most  apt  to  occur  near  or  at  the  lime- 
stone-greenstone  contact  was  not  successful,  and  the  field  evidence 
seems  to  indicate  that  copper  occurs  in  nearly  all  parts  of  the  forma- 
tion and  that  the  location  of  ore  bodies  is  dependent  only  on  favor- 
able conditions  of  supply  or  for  deposition. 

COPPER  SULPHIDE  DEPOSITS  IN  GREENSTONE  AND  LIMESTONE. 

Although  this  part  of  this  paper  is  intended  to  deal  only  with  the 
copper  prospects  of  the  Nizina  district,  it  is  necessary  in  the  descrip- 
tion of  the  ores  to  consider  the  district  in  its  relation  to  the  rest  of 
the  Chitina  region.  The  best  examples  of  copper  sulphides  in  green- 
stone are  not  found  within  the  region  under  consideration  but  to 
the  west  of  it.  The  copper  minerals  are  bornite,  chalcopyrite,  and 
chalcocite,  with  secondary  alteration  products,  and  they  occur  (1) 
in  irregularly  shaped  ore  bodies  without  any  conspicuous  amount  of 
associated  gangue  minerals  or  (2)  as  well-defined  veins  accom- 
panied by  a gangue  of  calcite  and  quartz.  Ore  bodies  of  the  first 
kind  occur  in  shear  zones  or  in  jointed  or  shattered  portions  of  the 
rock.  The  copper  minerals  fill  fractures  in  the  rock,  or  more  com- 
monly they  replace  the  rock  itself.  Bornite  and  chalcopyrite  are  of 
more  common  occurrence  than  chalcocite,  yet  some  of  the  most  prom- 
ising ore  bodies  in  the  greenstone  consist  chiefly  of  chalcocite. 

A careful  examination  of  the  many  copper  prospects  leads  to  the 
belief  that  most  of  the  ore  bodies  are  of  the  “ bunch  deposit  ” type 
and  are  a replacement  of  the  greenstone  by  copper  minerals  carried 
in  solutions  that  circulated  along  fracture  planes  produced  by  joint- 
ing, shearing,  or  faulting  of  the  country  rock.  The  mineralized  parts 
of  the  greenstone  are  without  definite  boundaries  in  many  places, 
and  the  ore  grades  from  solid  sulphides  to  disseminated  grains  or 
particles  scattered  through  the  greenstone,  which  grow  fewer  and 
fewer  as  distance  from  the  fractures  increases  till  they  disappear 
altogether.  Sections  of  ore  examined  under  the  microscope  show  that 
the  two  sulphides  bornite  and  chalcopyrite  are  closely  associated 
and  are  intermingled  in  such  a way  as  to  suggest  that  they  were 
deposited  at  the  same  time.  Chalcopyrite  is  practically  always  pres- 
ent, even  in  ore  that  appears  to  the  naked  eye  as  pure  bornite.  Chal- 
cocite accompanies  the  bornite  and  chalcopyrite  in  some  specimens, 
and  the  association  is  such  as  to  suggest  that  the  chalcocite  was 
derived  from  the  poorer  sulphides,  but  this  was  not  definitely  proved. 
A few  of  the  deposits  in  greenstone  consist  entirely  of  chalcocite. 


COPPER. 


79 


The  vein  deposits  accompanied  by  gangue  minerals  are  associated 
with  well-defined  faults  in  all  the  best  examples.  The  copper  min- 
erals are  bornite  and  chalcopyrite,  and  the  gangue  is  chiefly  calcite 
accompanied  by  quartz.  Epidote  is  commonly  present  also.  The 
veins  pinch  and  swell  markedly  in  short  distances  and  in  all  the 
localities  where  they  were  examined  have  been  subjected  to  faulting 
or  other  movement,  since  their  deposition. 

Copper  deposits  in  limestone  were  formed  by  replacement  of  the 
limestone  as  a whole  by  copper  minerals  in  solutions  circulating 
along  fracture  planes  such  as  faults,  shear  zones,  or  joints.  The  cop- 
per minerals  are  chalcocite  and  bornite,  accompanied  by  malachite, 
azurite,  and  in  places  covellite  as  alteration  products.  As  a rule, 
the  boundary  between  ore  and  country  rock  is  distinct,  although  the 
form  of  the  ore  body  itself  may  be  very  irregular.  This  is  particu- 
larly true  where  the  copper  mineral  is  chalcocite.  In  deposits  of 
bornite  in  limestone  a dissemination  of  the  copper  mineral  through 
the  adjacent  country  rock  was  noticed,  and  in  such  examples  there 
is  a gradation  from  ore  to  country  rock  similar  to  that  in  the  green- 
stone deposits.  One  of  the  best  examples  of  this  kind  shows  a large 
proportion  of  chalcocite  associated  with  the  bornite,  and  the  deposi- 
tion of  the  copper  was  accompanied  by  a thorough  silicification  of 
the  limestone.  Large  masses  of  chalcocite  like  that  of  the  Bonanza 
property  are  distinctly  replacement  deposits  in  fracture  zones.  No 
fragments  of  limestone  are  included  in  the  body  of  the  ore,  although 
isolated  masses  of  chalcocite  are  scattered  through  the  limestone. 
The  ores  are  most  frequent  near  the  limestone-greenstone  contact,  yet 
some  of  them  must  be  fully  1,000  feet  above  the  base  of  the  lime- 
stone. It  is  a notable  fact  that  azurite  is  far  more  common  as  a 
secondary  oxidation  product  in  the  limestone  replacement  deposits 
than  malachite  and  that  it  is  not  common  in  the  deposits  in  green- 
stone. Small  veins  of  azurite  with  cores  of  chalcocite  show  distinctly 
that  the  azurite  in  the  Bonanza  mine  was  produced  by  the  alteration 
of  chalcocite.  Covellite  originated  in  a similar  manner. 

NATIVE  COPPER  ASSOCIATED  WITH  THE  GREENSTONE. 

Native  copper  is  associated  with  amvgdaloidal  phases  of  the  Nikolai 
greenstone  and  is  also  found  accompanied  by  quartz  or  by  quartz  and 
epidote  in  veins  cutting  the  greenstone.  Most  commonly  it  occurs  as 
grains  and  small  slugs  in  the  amygdules  and  disseminated  through 
the  greenstone  and  as  films  or  leaves  and  small  veinlets  cutting  the 
greenstone.  Tabular  masses  deposited  in  joint  planes  without  much 
doubt  indicate  the  way  in  which  the  large  masses  of  native  copper 
and.  the  copper  nuggets  in  the  Dan  and  Chititu  placers  were  formed. 
Such  masses  found  in  place  on  the  head  of  White  River  are  believed 
to  have  resulted  from  the  alteration  of  chalcocite.  In  a few  places 


80 


THE  NIZINA  DISTRICT,  ALASKA. 


in  the  tributary  valleys  of  the  Chitistone  and  Kotsina  rivers  native 
copper  occurs  in  amygdaloidal  greenstone  in  association  with  a mix- 
ture of  copper  oxide  and  carbonaceous  matter,  filling  vesicles  and 
fractures  in  the  lavas.  Such  native  copper  as  is  known  in  the  Nizina 
district  is  probably  due  to  the  reduction  of  previously  formed  sul- 
phides or  oxides,  yet  primary  native  copper  is  known  on  the  head  of 
White  River.  There  is  a strong  similarity  between  the  native  copper- 
bearing greenstone  of  Chitina  Valley  and  the  amygdaloidal  copper 
ores  of  Lake  Superior.  Specimens  from  the  two  regions  could  be 
selected  between  which  it  is  doubtful  if  close  observation  could  distin- 
guish. This  similarity  would  also  extend  to  the  disseminated  sul- 
phide ores  in  greenstone  if  by  any  means  the  sulphides  could  be 
altered  to  native  copper. 

PLACER  COPPER. 

Native  copper  is  associated  with  silver  and  gold  in  the  gravels  of 
Chititu  and  Dan  creeks.  It  occurs  in  pieces  that  range  in  size  from 
fine  shot  to  masses  weighing  several  hundred  pounds.  Two  or  three 
tubs  of  fine  copper  are  secured  at  each  “ clean-up  ” of  the  sluice  boxes 
on  Chititu  Creek  and  give  much  difficulty  in  cleaning  the  gold,  since 
the  finest  of  the  copper  has  to  be  removed  by  hand.  Many  of  the 
nuggets  contain  native  silver,  which  shows  that  the  copper  and  silver 
are  here  closely  associated  in  origin.  The  remarkable  similarity  in 
form  and  appearance  between  the  copper  nuggets  of  the  Nizina  dis- 
trict and  the  larger  masses  of  copper  taken  from  the  stamp  mills  of 
the  Lake  Superior  region  is  evident  to  anyone  who  compares  the 
two,  since  the  chief  differences  are  that  the  placer  copper  has  a slightly 
smoother  surface  and  an  oxidized  coating.  The  copper  and  silver 
are  derived  wholly  or  in  part  from  the  greenstone.  Assays  of  clial- 
cocite  from  the  Bonanza  mine  and  from  other  copper  ores  of  the 
Nizina  district  have  shown  the  presence  of  both  silver  and  gold  in  the 
copper  deposits.  Small  particles  of  native  silver  were  found  in  a 
freshly  broken  specimen  of  greenstone  from  a bowlder  on  Chititu 
Creek,  and  an  assay  of  the  rock  also  showed  its  presence.  The  silver 
was  associated  with  calcite  in  small  fractures.  Silver  nuggets  up  to 
7 pounds  in  weight  have  been  found  on  Dan  and  Chititu  creeks, 
but  where  silver  is  associated  with  copper  in  the  same  nugget  copper 
predominates,  and  in  general  silver  is  seen  only  as  small  particles 
in  the  copper.  Copper  is  found  only  in  those  tributaries  of  Dan  and 
Chititu  creeks"  where  greenstone  pebbles  and  bowlders  form  part  of 
the  stream  gravels:  consequently  it  occurs  only  where  the  gravels 
have  been  formed  in  part  b}^  streams  flowing  through  greenstone 
areas  or  where  there  is  a foreign  element  in  the  gravels  that  was 
derived  from  a greenstone  area  and  brought  to  its  present  position 
by  glacial  ice. 


COPPER. 


81 


* ORIGIN  OF  THE  COPPER  DEPOSITS. 

It  is  not  yet  possible  to  give  a satisfactory  account  of  the  origin 
of  the  copper  deposits,  but  some  features  of  their  history  can  be 
stated  with  a considerable  degree  of  certainty,  and  it  is  desirable 
to  do  this,  since  it  may  be  of  value  in  future  development  work.  A 
history  of  the  present  deposits  is  concerned  chiefly  with  three  prob- 
lems— the  source  of  the  copper  minerals,  the  manner  in  which  they 
were  brought  to  their  present  position  and  deposited,  and  the  changes 
that  have  taken  place  in  them  since  they  were  deposited. 

It  is  believed  that  the  source  of  the  copper  is  within  the  Nikolai 
greenstone  itself  and  that  only  a very  small  part,  if  any,  is  derived 
from  an  outside  source.  The  chief  argument  in  favor  of  this  view 
is  the  widespread  and  almost  universal  occurrence  of  copper  miner- 
als in  the  greenstone  wherever  it  is  exposed.  This  is  seen  in  hun- 
dreds of  places  in  all  parts  of  the  formation,  from  the  west  end  of  the 
Chitina  Valley  to  Nizina  River  and  the  upper  Chitina.  Wherever 
fractures  in  the  greenstone  have  permitted  water  to  circulate  the 
green  copper  stain  is  apt  to  be  found.  Probably  the  copper  was 
originally  present  in  the  form  of  sulphide  in  the  lava  flows,  but 
this  does  not  exclude  the  possibility  of  its  also  having  been  combined 
in  other  minerals  of  the  rock.  Pyrite  and  chalcopyrite  are  of  com- 
mon occurrence  in  the  greenstone,  as  is  proved  by  both  the  hand 
specimens  and  the  thin  sections  examined  under  the  microscope. 
This  source  is  believed  to  be  adequate  for  supplying  all  the  copper 
concentrated  in  the  present  ore  bodies. 

An  examination  of  the  greenstone  in  many  places  has  shown  that 
considerable  chemical  alteration  in  its  constituent  minerals  is  uni- 
versal. No  fresh  and  unaltered  specimens  of  the  rock  were  found. 
Alteration  began  first  and  is  greatest  in  the  pyroxene,  and  in  ma no- 
places this  alteration  is  complete,  so  that  there  now  remains  only  a 
mass  of  chloritic  or  serpentinous  material.  The  feldspar  has  suf- 
fered less,  yet  the  changes  are  advanced.  Opaque  masses  of  brown 
iron  oxide  appear  to  represent  original  grains  or  crystals  of  pyrite 
or  chalcopyrite.  These  changes  have  resulted  in  the  production  of 
chloritic  and  possibly  serpentinous  material,  calcite,  quartz,  and 
delessite.  In  places  zeolites  as  thomsonite  have  been  produced,  but 
they  are  comparatively  rare  in  the  Nizina  district  and  the  region  to 
the  west,  although  they  are  abundant  in  amygdaloids  of  the  White 
River  region. 

Changes  of  the  kind  mentioned  • are  usually  considered  to  be 
accomplished  through  the  agency  of  circulating  water.  Chemical 
changes  in  the  minerals  of  the  basalts  were  made  possible  by  the 
presence  of  water  and  the  substances  carried  in  solution.  Ry  the 
same  means  copper  minerals  were  taken  into  solution  and  redeposited 
7064S°—  Bull.  443—11 G 


82 


THE  NIZINA  DISTRICT,  ALASKA. 


under  favorable  conditions.  It  is  a noteworthy  fact  that  the  Wran- 
gell Mountain  region  has  been  one  of  volcanic  activity  since  Car- 
boniferous time  at  least,  and,  although  it  has  not  been  possible  to 
establish  a direct  relation  between  the  copper  deposits  and  any 
igneous  rocks  of  later  age  than  the  Nikolai  greenstone,  it  is  not 
unreasonable  to  suppose  that  the  presence  of  heated  rocks  in  the  near 
vicinity  may  have  had  an  important  influence  in  promoting  circula- 
tion in  the  greenstone  and  particularly  in  increasing  the  solvent 
power  of  the  circulating  water. 

As  to  the  manner  of  deposition,  it  is  believed  that  the  copper  taken 
into  solution  by  circulating  water  was  carried  into  trunk  channels 
and  deposited  there  when  the  conditions  were  favorable.  Specula- 
tions as  to  the  exact  chemical  changes  that  took  place  are  of  very 
doubtful  value  with  the  present  knowledge  of  the  facts  and  will  not 
be  attempted.  Most  frequently  deposition  took  place  in  the  green- 
stone formation,  but  at  times  the  copper-bearing  waters  passed  out- 
side the  greenstone  and  into  the  overlying  limestone  before  giving 
up  their  mineral  load.  As  a rule,  the  ore  bodies  were  not  formed  by 
the  deposition  of  copper  minerals  in  open  cavities,  although  openings 
sufficient  to  permit  a circulation  of  water  were  necessarily  present. 
Most  of  the  ore  is  a replacement  of  the  country  rock  itself  by  copper 
sulphides.  The  replacement  of  greenstone  is  more  nearly  complete 
adjacent  to  the  openings  through  which  water  passed  and  grows  less 
and  less  as  the  distance  from  the  openings  increases.  On  the  other 
hand,  most  of  the  limestone  ores  show  a complete  replacement  of 
the  limestone  without  any  outside  zone  of  disseminated  sulphides. 

Examination  with  the  microscope  has  shown  that  bornite  and 
chalcopyrite  are  usually  associated  in  the  greenstone  deposits,  even 
in  bornite  ores  that  show  no  chalcopyrite  to  the  unaided  eye.  This 
fact,  together  with  the  manner  in  which  chalcopyrite  is  scattered 
through  the  bornite,  might  be  taken  as  presumptive  evidence  that 
the  bornite  was  derived  from  chalcopyrite  and  is  a secondary  enrich- 
ment. This  fact  alone  does  not  amount  to  proof,  but  the  seeming 
increase  in  chalcopyrite  as  depth  is  gained  in  some  of  the  bornite- 
chalcopyrite  veins,  such  as  the  Nikolai  vein,  lends  some  weight  to  the 
presumption.  The  presence  of  native  copper  associated  with  chalco- 
cite  and  bornite  also  points  to  the  same  conclusion,  since  native  copper 
is  usually  regarded  as  of  secondary  origin.  On  the  other  hand,  no 
evidence  was  found  in  the  chalcocite  deposits  in  limestone,  such  as 
that  of  the  Bonanza  mine,  to  indicate  that  the  ore  body  has  ever  been 
anything  other  than  what  it  is  at  present.  The  copper  sulphide 
appears  to  have  been  deposited  as  such,  and  a careful  examination 
of  the  ore  has  failed  to  discover  the  presence  of  other  minerals  than 
those  produced  by  alteration  of  the  chalcocite.  It  is  doubtful  if  sec- 
ondary enriched  ores  could  form  under  the  conditions  now  prevailing 


COPPER. 


83 


at  the  Bonanza  mine,  since  all  openings  such  as  are  due  to  joints  and 
other  fractures  are  filled  with  ice,  as  is  also  the  loose  talus  material 
below  the  mine  on  both  sides  of  the  ridge.  Furthermore,  the  break- 
ing down  of  the  ore  and  of  the  limestone  inclosing  the  ore  body 
under  the  climatic  conditions  of  this  region  proceeds  faster  than 
oxidation.  The  exposed  ore  on  the  ridge  and  loose  broken-down  ore 
on  the  talus  slopes  show  only  a thin  film  of  oxidized  material  on 
the  surface.  Yet  thin  veins  of  chalcocite  in  the  limestone  and  even 
large  masses  of  chalcocite  have  been  almost  completely  altered  to 
azurite,  which  shows  that  oxidation  has  taken  place  either  under 
present  conditions  or,  more  probably,  under  earlier  and  more  favor- 
able conditions,  possibly  before  the  late  ice  advance. 

The  ore  of  the  Westover  claim,  on  Dan  Creek,  is  an  intimate 
mixture  of  chalcocite  and  bomite  in  silicified  limestone  along  a frac- 
ture zone.  The  copper  and  copper-iron  sulphides  are  disseminated 
through  the  rock  in  small  grains  and  in  veinlets  cutting  the  rock. 
Most  of  the  disseminated  grains  are  chalcocite,  but  the  veinlets  and 
the  larger  irregular  masses  are  a mixture  of  chalcocite  and  bornite. 
The  veinlets  are  later  than  the  quartz  inclosing  them  and  pos- 
sibly later  than  the  disseminated  grains  in  the  quartz,  yet  the 
minerals  of  the  veinlets  appear  to  be  contemporaneous.  These 
examples  show  how  unsatisfactory  is  the  evidence  concerning  the 
nature  of  the  deposits,  but  they  have  some  importance  in  that  they 
do  not  promise  greater  richness  in  copper  as  the  ores  are  followed 
below  the  surface.  This  point  is  emphasized  because  of  the  belief 
on  the  part  of  many  prospectors  in  the  Chitina  region  that  the  de- 
posits will  grow  richer  as  they  are  more  fully  developed.  The  con- 
trary is  more  likely  to  be  true,  for  although  they  may  continue  with 
their  present  richness  they  are  more  apt  to  grow  poorer  than  to 
grow  richer. 

DESCRIPTION  OF  PROPERTIES. 

PRINCIPAL  GROUPS. 

The  better-known  copper  properties  of  the  Nizina  district  may  be 
divided  into  three  groups — first,  the  group  in  the  vicinity  of  Bonanza 
Peak,  including  the  Bonanza  mine,  the  Jumbo,  the  Erie,  and  the 
Independence  claims,  together  with  the  properties  known  as  the  Mar- 
vellous and  Bonanza  extension  claims;  second,  the  Nikolai  Creek 
group;  and,  third,  the  group  that  includes  the  Westover  claim  and 
other  neighboring  claims  north  of  Dan  Creek.  Many  other  claims 
have  been  staked,  particularly  along  the  limestone-greenstone  contact, 
but  there  has  been  little  development  work  done  on  them  and  they  con- 
tribute little  to  our  knowledge  of  the  copper  deposits  of  the  district. 


84 


THE  NIZINA  DISTRICT,  ALASKA. 


BONANZA  MINE. 

The  Bonanza  mine  is  the  most  valuable®  copper  property  now 
known  in  the  Copper  River  region.  It  is  situated  on  the  east  side  of 
Kennicott  Glacier,  at  the  head  of  Bonanza  Creek,  and  is  the  property 
of  the  Kennicott  Mines  Company.  Bonanza  Creek  proper  and  its 
western  fork  head  in  a glacial  cirque  basin  on  the  west  side  of  the 
high  divide  between  Kennicott  Glacier  and  McCarthy  Creek.  Its 
two  forks  include  the  high  ridge  on  which  the  copper  deposit  is 
situated.  The  stream  is  about  3 miles  long  and  flows  in  a south- 
westerly direction  to  the  Kennicott  Glacier.  A post-office  called 
Kennicott  has  been  established  at  the  mouth  of  National  Creek, 
half  a mile  south  of  the  mouth  of  Bonanza  Creek  and  4 miles  from 
the  mine,  and  the  company’s  main  camp  and  office  are  located  at  that 
place.  A wagon  road  leads  from  the  mouth  of  National  Creek  to 
a point  about  500  feet  below  the  mine  and  another  follows  the  edge 
of  the  glacier  south  to  McCarthy  Creek.  An  aerial  tram  with  a 
capacity  of  100  tons  per  day  has  been  constructed  and  loading  and 
delivery  stations  have  been  built,  so  that  the  mine  is  now  practically 
ready  to  begin  the  production  of  ore,  although  the  storage  bunkers 
are  not  completed  and  no  ore  can  be  shipped  till  the  railroad  reaches 
Kennicott. 

An  examination  of  the  geologic  map  (PI.  Ill,  in  pocket)  will 
make  clear  the  general  geologic  conditions.  South  of  National  Creek 
the  high  ridge  between  the  glacier  and  McCarthy  Creek  consists  of 
black  Kennicott  shale  intruded  by  large  masses  of  light-grav  por- 
phyry. The  Jurassic  shales  and  intrusives  are  separated  b}T  an  un- 
conformity and  probably  also  by  a fault  from  the  greenstone  and  the 
overlying  Chitistone  limestone  on  the  north.  North  of  National 
Creek  the  greenstone  and  limestone  appear.  The  strike  of  the  lime- 
stone is  northwest  and  southeast,  and  its  dip  averages  between  25° 
and  35°  NE.  It  therefore  cuts  diagonally  across  the  main  ridge 
from  McCarthy  Creek  to  the  glacier.  Still  farther  northeast  the 
Triassic  shales  overlying  the  limestone  appear,  but  are  not  of  any 
importance  in  connection  with  the  copper. 

The  Bonanza  mine  is  situated  on  a spur  that  runs  out  to  the  south- 
west between  the  forks  of  Bonanza  Creek  from  the  main  ridge.  This 
spur  is  crossed  by  the  limestone-greenstone  contact  at  a point  about 
one-third  of  a mile  from  the  main  ridge.  Where  the  boundary 
crosses  the  crest  of  this  spur  it  has  an  elevation  of  G,000  feet  above 
sea  level  or  4,000  feet  above  the  point  at  the  mouth  of  National  Creek 
where  the  tramway  will  deliver  ore.  On  the  northeast  the  spur 

° Since  the  Bonanza  mine  was  visited  in  1907  much  work  has  been  done  toward  surface 
development  and  equipment  of  the  mine  for  shipping  ore,  but  work  on  the  ore  body  itself 
has  not  been  such  as  to  add  greatly  to  the  knowledge  of  the  deposit.  For  this  reason  the 
description  here  given  is  based  largely  on  the  previous  description  published  in  Bull.  U,  S. 
Geol.  Survey  No.  374, 


BULLETIN  448  PLATE  XII 


WEST  SIDE  OF  RIDGE  AT  BONANZA  MINE. 

The  richest  ore  exposed  on  the  surface  is  on  the  top  and  face  of  the  ridge  between  the  points  indicated  by  arrows.  See  page  85. 


COPPER. 


85 


rises  rapidly  till  1,000  feet  in  elevation  is  gained,  but  on  the  south- 
west its  crest  is  almost  horizontal  for  a distance  of  about  one-third 
of  a mile,  beyond  which  it  slopes  away  steeply  to  the  forks  of  Bo- 
nanza Creek  (PI.  XII). 

The  greenstone  immediately  below  the  ore  body  is  variable  in 
texture  and  general  appearance.  Part  of  it  is  amygdaloidal ; por- 
phyritic  phases  are  also  present.  Amygdules  are  not  confined  to  the 
top  of  the  flows  but  are  present  throughout  from  bottom  to  top.  In 
some  places  they  have  been  dissolved  out  on  exposed  surfaces,  leaving 
a vesicular  rock  that  looks  like  a recent  lava.  A bed  of  red  and  green 
shale  having  a thickness  of  about  5 feet  intervenes  between  the  green- 
stone and  the  overlying  limestone.  This  shale  forms  a narrow  north- 
ward-sloping bench  for  a short  distance  along  the  northwest  side  of 
the  ridge,  but  is  everywhere  covered  with  talus  and  is  found  only 
when  the  debris  has  been  cleared  away.  The  bench  is  clearly  indi- 
cated by  the  snow  banks  in  Plate  XII.  The  base  of  the  lime- 
stone consists  of  not  less  than  40  feet  of  coarse  gray,  slightly  argil- 
laceous rock,  whose  broken  surfaces  are  covered  in  many  places  with 
flattened  cylindrical  bodies  that  immediately  suggest  organic  material 
of  some  kind.  Several  specimens  of  these  bodies  were  submitted  to 
Dr.  T.  W.  Stanton,  who  says  that  they  are  probably  corals  but  are 
too  obscure  for  identification.  Over  this  basal  limestone  is  a bed  a 
few  feet  thick  of  impure  shaly  limestone,  and  this  in  turn  is  over- 
lain  by  dark  and  light-gray  massive  beds  which  carry  the  ore  bodies. 
The  limestone  dip  at  the  mine  is  slightly  variable  but  averages  about 
22°  NE. 

The  limestone  is  broken  by  numerous  faults  and  fracture  planes, 
the  most  prominent  of  which  are  nearly  perpendicular  and  range  in 
strike  from  N.  40°  E.  to  N.  70°  E.  A minor  set  of  fault  planes  with 
about  the  same  strike  dips  steeply  to  the  west.  Another  set  runs  in 
a northwesterly  direction,  and  in  several  places  striations  on  slicken- 
sided  surfaces  or  clay  seams  show  that  the  movement  was  horizontal. 
Fault  planes  with  low  dips,  some  of  them  nearly  horizontal,  are  also 
present.  None  of  the  faults  observed  give  evidence  of  much  displace- 
ment, but  together  with  the  numerous  joints  they  afforded  an  oppor- 
tunity for  mineral-bearing  waters  to  enter  the  limestone.  The  prin- 
cipal fault  planes — those  running  from  northeast  to  southwest — form 
what  may  be  described  as  a sheeted  zone  in  the  limestone  that  was 
traced  north-northeast  from  the  Bonanza  mine  for  1^  miles.  This 
zone  has  a width  of  50  or  60  feet  and  extends  through  the  shale  bed 
into  the  greenstone  below,  but  is  less  noticeable  in  the  greenstone 
than  in  the  limestone.  A vertical  displacement  of  2 feet  occurs  in  the 
limestone-greenstone  contact  along  one  of  the  fault  planes  in  the 
shear  zone  and  is  the  maximum  displacement  observed. 


86 


THE  NIZINA  DISTKICT,  ALASKA. 


The  copper  ore  is  chalcocite.  Considerable, azurite  has  been  formed 
by  oxidation  of  the  chalcocite,  and  covellite  is  reported  also.  Covel- 
lite  was  not  found  in  the  specimens  of  ore  collected  from  the  Bonanza 
mine  by  the  writers,  but  good  specimens  of  covellite  were  collected 
from  the  Marvellous  claim  half  a mile  to  the  northeast,  and  its  occur- 
rence at  the  Bonanza  is  not  questioned.  The  chalcocite  is  in  veins 
or  tabular  masses  of  solid  ore  up  to  5 or  6 feet  in  thickness,  in  large 
irregularly  shaped  bodies,  and  in  stockworks  in  the  brecciated  lime- 
stone. Two  principal  veins  of  chalcocite  are  seen  on  the  surface. 
They  stand  almost  perpendicularly,  12  to  15  feet  apart,  and  strike 
N.  41°  E.,  forming  the  comb  of  the  sharp  ridge  but  crossing  it  at  a 
slight  angle,  as  the  ridge  at  this  place  has  a more  nearly  north-south 
direction  than  the  veins.  On  the  surface  the  veins  do  not  extend 
down  into  the  lower  impure  part  of  the  limestone  but  end  abruptly 
on  reaching  it.  In  places  the  precipitous  northwest  face  of  the  ridge 
is  plastered  over  with  masses  of  solid  chalcocite  for  a distance  of  50 
or  60  feet  vertically  below  the  top. 

Azurite  appears  on  the  surface  of  the  chalcocite  and  also  as  a lining 
of  small  vugs  in  the  chalcocite,  but  it  is  present  chiefly  as  thin  veins, 
that  form  a network  in  the  limestone  and  are  doubtless  due  to  the 
alteration  of  original  chalcocite  veins,  for  some  of  the  azurite  has  an 
inner  core  of  chalcocite.  Azurite  is  more  conspicuous  than  chalcocite 
in  the  surface  network  of  veins  in  the  northern  150  feet  of  the  ore 
body,  but  chalcocite  forms  the  great  mass  of  the  remainder.  The  ore 
bodies  formed  along  the  northeast-southwest  faults  of  the  northern 
part  of  the  deposit  are  not  the  direct  continuation  of  the  large  chalco- 
cite veins  at  the  south,  but  lie  in  nearly  parallel  veins  which  cut  the 
ridge  at  a greater  angle,  their  strike  being  about  N.  60°  to  70°  E. 
The  very  rich  ore  can  be  traced  on  the  surface  for  a distance  of  about 
250  feet.  It  ends  abruptly  on  the  south  in  a nearly  vertical  limestone 
wall,  but  on  the  north  gives  place  to  the  lower-grade  ores,  consisting 
of  small  veins  of  azurite  and  chalcocite  with  scattered  masses  of 
chalcocite,  some  of  them  weighing  several  tons.  This  lower-grade  ore 
shows  on  the  surface  for  a distance  of  at  least  150  feet  northeast  from 
the  high-grade  ores,  and  small  scattered  azurite  veins  extend  still 
farther  in  that  direction.  The  ore,  as  it  shows  on  the  surface,  there- 
fore, extends  northeast  and  southwest  along  the  strike  for  a distance 
of  400  feet.  The  thickness,  however,  is  more  indefinite,  but  the  very 
rich  ore,  with  its  included  limestone,  as  seen  at  the  surface,  has  a width 
of  approximately  25  feet,  although  the  thickness  of  ore  sufficiently 
rich  to  be  mined  may  be  greater. 

A little  chalcocite  and  less  bornite  are  found  in  some  of  the  shearing 
planes  in  the  greenstone,  but  they  do  not  extend  far  into  the  green- 
stone. The  quantity  is  small  and  inconspicuous  and  might  readily 
pass  unobserved.  A small  amount  of  epidote  is  associated  with  it  in 


COPPER. 


87 


places.  The  main  shear  zone  in  the  greenstone  cuts  an  older  set  of 
quartz-epidote  veins  whose  direction  is  about  north-northwest.  These 
veins  do  not  intersect  the  limestone.  They  reach  a maximum  thick- 


Figure  5. — Sketch  map  of  the  area  near  the  Bonanza  mine,  showing  the  limestone- 
greenstone  contact,  the  location  of  the  richer  ores  on  the  surface,  and  the  tunnels. 

ness  of  1 foot  and  carry  small  amounts  of  chalcocite,  bornite,  and 
native  copper. 

When  the  Bonanza  mine  was  visited  in  1907  two  crosscuts  (fig.  5) 
had  been  driven  in  the  ore  body  in  a direction  N.  33°  W.  They  are 


88 


THE  NIZINA  DISTRICT.  ALASKA. 


therefore  not  exactly  perpendicular  to  it.  The  longer  tunnel  starts 
on  the  east  side  of  the  ridge  and  75  feet  below  its  top ; it  is  180  feet  in 
length  and  extends  through  to  the  west  side  of  the  ridge.  The  richest 
ore,  consisting  of  large  masses  of  chalcocite  with  some  included  lime- 
. stone,  is  encountered  at  a distance  of  90  feet  from  the  tunnel’s  mouth 
and  continues  for  a distance  of  21^  feet  as  measured  in  the  roof. 
There  are  smaller  bodies  of  chalcocite,  however,  for  a distance  of  10 
or  15  feet  on  either  side  of  the  main  ore  body.  About  115  feet  from 
the  entrance  to  the  tunnel  a winze  83  feet  deep  was  sunk  in  the 
ore,  and  from  the  bottom  a drift  zigzags  northward  approximately 
110  feet. 

In  1909  a new  tunnel  had  been  driven  below  this  longer  tunnel 
from  the  southeast  side  of  the  ridge  and  connected  by  a raise  wdth 
the  winze.  The  new  t.unnel  is  78  feet  below  the  upper  one  and 
parallel  with  it.  Tn  July,  1909,  it  had  been  driven  45  feet  beyond 


Figure  6. — Sketch  showing  form  of  ore  body  exposed  in  the  upper  northern  tunnel  at  the 

Bonanza  mine. 


the  raise  but  had  not  encountered  any  ore  bodies  as  large  as  those 
of  the  upper  tunnels.  Several  small  lenses  of  chalcocite,  the  largest 
about  18  inches  thick,  were  exposed  in  the  tunnel  itself,  but  the  raise 
showed  much  more,  for  it  cut  the  large  body  in  which  the  winze 
was  sunk.  The  absence  of  the  large  chalcocite  bodies  in  the  lower 
tunnel  adds  some  weight  to  the  opinion  expressed  after  the  visit  of 
1907  that  the  ore  would  probably  not  extend  into  the  basal  impure 
limestone  beds. 

About  120  feet  southwest  of  this  tunnel  is  a parallel  tunnel  driven 
from  the  west  side  of  the  ridge  and  50  feet  lower  than  the  little  saddle 
above  it  on  the  north.  This  tunnel  starts  in  a face  of  solid  chalco- 
cite and  extends  S.  33°  E.  for  50  feet.  The  ore,  which  is  chalcocite 
with  a small  amount  of  azurite,  is  exposed  for  34  feet  along  the  tun- 
nel, but  is  interrupted  by  horses  of  limestone.  The  remainder  of 
the  tunnel  shows  limestone  cut  by  small  azurite  veins  and  in  places 
containing  a small  amount  of  chalcocite. 


COPPER. 


89 


A better  conception  of  the  form  of  the  ore  bodies  can  be  obtained 
by  an  examination  of  figures  5,  6,  and  7 than  can  be  given  in  a 
written  description.  The  two  main  parallel  surface  veins  afford 
only  an  imperfect  idea  of  the  deposit.  Those  two  veins  represent  a 
total  replacement  of  limestone  along  minor  zones,  where  shearing 
was  most  intense.  The  two  tunnels  show  that  not  only  is  the  lime- 
stone replaced  along  the  main  shear  zone  but  that  mineralized  waters 
followed  minor  fracture  planes  also,  and  thus  yielded  the  low-lying 
ore  bodies  and  great  irregular  masses  seen  underground.  Between 
and  around  the  large  masses  of  clialcocite  the  limestone  was  shattered 
and  filled  with  many  small  veins  of  ore,  which  formed  a stockwork 
that  is  most  noticeable  in  the  winze  tunnel  and  on  the  surface  north- 
east of  the  main  ore  body.  As  a rule,  the  brittle  chalcocite  is  very 
little  fractured.  The  limestone,  on  the  other  hand,  is  greatly  shat- 
tered and  is  filled  with  thin  veins  of  calcite  which  are  older  than 


SW.  wall 


NW. 


NE.  wall 


0 ^ 5 10 15 20  feet 

Figure  7. — Sketch  showing  form  of  ore  body  exposed  in  the  southern  tunnel  at  the 

Bonanza  mine. 

the  ore  deposition.  Open  cavities  in  the  fractured  limestone  have 
been  filled  with  ice,  and  both  the  country  rock  and  the  talus  on  either 
side  of  this  ridge,  except  for  a few  feet  at  the  surface,  are  frozen 
all  summel*.  The  talus  slopes  below  the  ore  body  contain  a large 
quantity  of  chalcocite  resulting  from  weathering  of  the  veins  above 
and  are  a valuable  source  of  copper. 

It  is  a suggestive  fact  that,  although  the  main  shear  zone  of  the 
Bonanza  mine  extends  from  the  limestone  through  the  thin  shale 
bed  into  the  greenstone  below,  the  large  chalcocite  bodies,  so  far  as 
can  be  determined  on  the  surface,  end  abruptly  at  the  top  of  the  im- 
pure shaly  beds  forming  the  lower  50  or  60  feet  of  the  limestone. 
Copper  minerals  are  associated  with  the  shear  zone  in  the  greenstone, 
but  only  in  small  amount.  Apparently  the  impure  thin-bedded  part 
of  the  limestone  was  a less  favorable  place  for  deposition  than  the 
purer  massive  beds  above.  This  fact  has  a practical  bearing  on  the 
quantity  of  ore  present,  for  it  is  evident  that  if  the  same  condition 


90 


THE  NIZINA  DISTRICT,  ALASKA. 


continues  underground  it  limits  the  downward  extension  of  chal- 
cocite  in  the  limestone.  The  continuation  of  the  ore  body  to  the  north- 
east will  probably  be  limited  chiefly  by  the  continuation  of  favorable 
conditions  for  deposition  in  the  shear  zone  in  that  direction.  The 
exact  conditions  wdiich  determined  the  deposition  of  the  Bonanza 
ore  body  are  not  known;  possibly  it  was  the  presence  of  a shear 
zone  favorable  to  circulation;  but  its  occurrence,  together  with  that 
of  the  Jumbo  and  the  Erie  chalcocite  bodies  to  the  northwest,  next 
to  be  described,  indicates  that  favorable  conditions  for  deposition 
have  been  established  in  more  than  one  place  and  offer  encouragement 
for  seeking  other  chalcocite  bodies  at  the  base  of  the  Chitistone  lime- 
stone. 

JUMBO  CLAIM. 

From  the  Bonanza  mine  the  Chitistone  limestone  continues  north- 
westward in  a succession  of  lofty  cliffs  as  far  as  Kennicott  Glacier. 
The  base  of  these  cliffs  is  at  the  greenstone  contact  and  in  many 
places  contains  veinlets  and  stringers  of  azurite  or  chalcocite.  In 
at  least  two  places  the  quantity  of  these  two  minerals,  especially  of 
the  chalcocite,  is  so  great  as  to  make  the  deposits  of  commercial 
importance. 

The  ore  body  of  the  Jumbo  claim  is  4, GOO  feet  northwest  of  the 
Bonanza,  at  the  head  of  Jumbo  Creek,  and  is  located  in  limestone 
just  above  the  greenstone-limestone  contact  on  a small  southwestward 
projecting  spur  or  angle  of  the  limestone  cliff.  South  of  it  and  nearly 
200  feet  below  is  the  glacier  in  which  Jumbo  Creek  heads  and  which 
must  be  crossed  to  reach  the  ore  body.  The  Jumbo  and  Bonanza  ore 
bodies  are  at  practically  the  same  elevation  above  sea  level,  approxi- 
mately 6,000  feet. 

The  limestone  at  the  Jumbo  is  made  up  near  the  base  of  slightly 
cherty  beds  ranging  in  thickness  from  8 to  12  inches.  The  strike 
is  N.  65°  W.,  the  dip  35°  N.  A tunnel  12  feet  loiig  was  started  on  the 
south  face  of  the  ridge,  10  feet  above  the  greenstone.  The  limestone 
is  jointed  or  cut  by  minor  faults  parallel  to  the  bedding  and  is  crossed 
by  veins  of  calcite  from  1 to  2 inches  thick.  Thin  veins  of  chalcocite 
and  azurite  accompany  them  and  fill  some  of  the  fractures.  Seven 
feet  above  the  tunnel  mouth  is  the  east  end  of  a large  chalcocite  mass 
which  is  well  exposed  on  the  axis  of  the  ridge.  As  indicated  on  the 
surface,  this  body  of  ore  is  a mass  of  solid  chalcocite  30  feet  long, 
6 feet  by  4 feet  6 inches  at  the  west  end,  and  tapering  to  a diameter 
of  1 foot  at  the  east  end.  It  appears  to  be  a rudely  lenticular  or 
possibly  a conical  body,  but  has  irregularly  shaped  protuberances,  as 
may  be  seen  at  the  west  end,  where  the  steep  west  face  or  slope  of  the 
spur  gives  a cross  section  of  the  ore  body.  (See  fig.  8.) 

A little  way  east  of  the  Jumbo  tunnel  is  a second  tunnel  in  lime- 
stone a short  distance  above  the  greenstone.  The  tunnel  runs  nearly 


COPPER. 


91 


north  or  slightly  to  the  northeast  in  limestone  that  strikes  N.  65°  W. 
and  dips  25°  N.  In  the  tunnel,  which  is  12  feet  long,  the  limestone 
is  crushed  and  jointed.  Small  veins  of  calcite  and  azurite  up  to  2J 
inches  in  thickness  fill  joint  cracks,  especially  a set  of  perpendicular 
minor  faults  or  slip  planes  running  N.  70°  W.  No  chalcocite  is  ex- 
posed in  this  tunnel,  but  it  is  believed  that  the  azurite  indicates  its 
former  presence.  Fifty  feet  below  the  tunnel  a lenticular  vein  of 
chalcocite  3 inches  thick  at  its  widest  part  and  3 feet  long  was  found 
in  the  limestone. 


0 , , , , 5 10 15  20  feet 

Figure  8. — Sketch  of  the  ore  bodj7  at  the  Jumbo  claim. 

ERIE  CLAIM. 

The  Erie  claim  is  the  property  of  the  Kennicott  Mines  Company 
and  is  situated  on  a steep  mountain  slope  near  the  east  side  of  Kenni- 
cott Glacier,  3f  miles  north  of  Kennicott,  at  the  mouth  of  National 
Creek.  The  discovery  point  is  a little  more  than  1,000  feet  above  the 
nearest  point  of  the  glacier  and  is  at  the  limestone-greenstone  contact, 
which  here  strikes  N.  78°  W.  and  dips  38°  N.  Between  the  limestone 
and  the  greenstone  is  a bed  of  greenish  shale  of  variable  thickness, 
but  ranging  from  12  to  18  inches.  There  is  also  a very  thin  bed  of 
shale  not  more  than  1 inch  thick  in  the  limestone  8 inches  above  the 
base.  There  appears  to  have  been  movement  between  the  limestone 
and  the  greenstone  along  their  plane  of  contact,  and  they  were 
further  disturbed  by  small  faults  cutting  across  the  contact  at  high 
angles  to  the  bedding  in  such  a way  that  at  one  place  a wedge  of 
greenstone  projects  into  the  limestone.  The  larger  shale  bed  contains 
many  nodules  of  chalcopyrite  from  one-half  inch  to  2 inches  in 
diameter,  and  with  the  chalcopyrite  there  is  associated  more  or  less 


92 


THE  NIZINA  DISTKICT,  ALASKA. 


bornite  in  the  larger  nodules.  Abundant  scales  of  azurite  are  scat- 
tered through  the  shale.  No  development  work  has  been  done  on  this 
claim  further  than  to  clear  away  the  debris  and  make  an  open  cut 
along  the  contact  so  as  to  expose  the  copper-bearing  shale. 

INDEPENDENCE  CLAIMS. 

The  Independence  group  of  claims,  belonging  to  the  Kennicott 
Mines  Company,  is  on  the  east  side  of  the  divide  that  separates  the 
head  of  Bonanza  Creek  from  McCarthy  Creek  and  is  from  900  to 
1,000  feet  lower  than  the  saddle  where  the  limestone-greenstone  con- 
tact crosses  the  ridge.  The  copper  minerals  occur  in  small  veins  that 
contain  considerable  calcite  and  belong  to  a sheeted  zone  striking 
N.  38°  E.,  thus  crossing  the  contact  almost  at  right  angles.  This 
zone  passes  from  the  greenstone  into  the  limestone  and  has  its  great- 
est width  (about  50  feet)  at  the  contact.  The  ore  is  found  in  the 
greenstone  only  and  consists  essentially  of  chalcocite,  which  fills  frac- 
tures and  is  disseminated  through  the  greenstone.  It  is  later  than  the 
calcite  filling  of  the  sheeted  zone  and  gradually  disappears  with 
increasing  distance  from  the  zone  of  mineralization.  The  main  shear 
zone  intersects  a system  of  quartz-epidote  veins  striking  N.  78°  E. 
and  carrying  a small  amount  of  bornite.  There  is  a marked  similar- 
ity between  the  occurrence  of  copper  sulphides  in  the  greenstone  at 
this  locality  and  at  the  Bonanza  mine,  but  there  is  no  chalcocite  body 
in  the  limestone  of  the  Independence  claim. 

MARVELLOUS  AND  BONANZA  EXTENSION  CLAIMS. 

The  shear  zone  in  which  the  Bonanza  ore  was  deposited  extends  in 
a direction  about  N.  30°  E.  from  the  Bonanza  mine  for  a distance  of 
more  than  a mile.  It  crosses  the  saddle  between  Bonanza  Creek  and 
the  glacier  on  the  north  and  extends  to  the  high  point  of  the  ridge 
running  northeast  from  Bonanza  Peak.  It  was  not  traced  beyond 
that  point.  There  is  no  evidence  of  displacement,  but  there  is  a shear 
zone  of  indefinite  width  made  up  of  innumerable  small  parallel  frac- 
tures filled  with  calcite  and  crossed  by  minor  fault  planes.  These 
fault  planes  are  believed  to  have  had  an  important  and  perhaps  a 
controlling  influence  in  the  deposition  of  copper. 

All  the  Bonanza  fault  northeast  of  the  Bonanza  property  is  owned 
by  the  Mother  Lode  Copper  Mines  Company  and  the  Houghton  Alaska 
Exploration  Company.  The  principal  exposures  of  copper  minerals 
are  on  the  Marvellous  claim,  where  a number  of  short  tunnels  have 
been  driven.  The  Marvellous  claim  is  on  the  north  side  of  the  glacier 
east  of  Bonanza  Peak  and  is  about  2,800  feet  above  the  valley  of 
McCarthy  Creek. 

At  the  south  tunnel  of  the  Marvellous  the  limestone  is  cut  by 
numerous  closely  spaced  parallel  joint  or  shear  planes,  many  of  which 


COPPER. 


93 


are  filled  with  calcite  and  are  conspicuous  because  they  are  lighter  in 
color  than  the  surrounding  limestone.  They  strike  N.  70°  E.  and  dip 
70°  to  80°  N.  The  tunnel  is  15  feet  under  cover  and  exposes  a vein 
of  chalcocite  from  3 to  6 inches  wide  striking  N.  60°  W.  About  30 
feet  north  of  the  tunnel’s  mouth  and  25  feet  lower  is  a vein  of  chalco- 
cite in  calcite  that  reaches  a maximum  thickness  of  9 inches.  It 
strikes  N.  60°  E.  and  dips  60°  to  65°  W.  The  vein  is  in  a well- 
defined  fault  plane  and  can  be  traced  for  nearly  200  feet  from  the 
tunnel’s  mouth.  In  places  it  pinches  to  a thickness  of  1 inch  and 
carries  no  ore.  Fine  specimens  of  covellite  in  chalcocite  were  ob- 
tained from  this  locality.  There  is  a second  parallel  vein  12  feet  to 
the  north,  but  it  is  not  so  long. 

The  main  tunnel  of  the  Marvellous  is  300  feet  northeast  of  the 
south  tunnel  and  runs  100  feet  S.  85°  W.  in  dark-gray  limestone.  The 
vein  is  a stockwork  of  small  calcite  veins,  with  chalcocite  and  azurite 
in  crushed  limestone.  About  20  feet  from  the  face  is  a crosscut  9 feet 
long  where  there  is  a vertical  fissure  in  the  limestone  striking  N.  25° 
E.  The  fissure  is  filled  with  calcite  and  carries  chalcocite  and  azurite. 
It  has  a thickness  of  6 inches.  The  limestone  is  much  discolored  by 
iron  oxide.  Above  the  tunnel  is  a large  mass  of  azurite  formed  by 
the  oxidation  of  chalcocite  whose  downward  extension  the  tunnel 
was  expected  tp  strike. 

A third  tunnel,  called  the  north  tunnel,  was  started  on  the  Mar- 
vellous claim  200  feet  northeast  of  the  main  tunnel  and  100  feet 
above  it.  The  copper  minerals  at  this  exposure  occur  along  bedding 
planes  of  the  limestone,  which  here  strikes  N.  40°  W.  and  dips  35°  E., 
and  along  fault  planes  that  cross  the  bedding.  The  faults  strike  N. 
10°  W.  and  dip  44°  E. 

NIKOLAI  CLAIM. 

The  Nikolai  claim  is  located  near  the  head  of  Nikolai  Creek,  3f 
miles  northeast  of  the  junction  of  Nikolai  and  McCarthy  creeks  and 
2,150  feet  above  it.  The  exposed  ore  body  is  situated  near  the  top 
of  the  greenstone  formation,  about  150  feet  below  the  base  of  the 
limestone,  and  is  associated  with  a fault  which  cuts  the  limestone- 
greenstone  contact  at  this  place.  It  is  composed  mainly  of  chalcopy- 
rite  and  bornite  stained  with  oxidation  products. 

An  examination  of  figure  9 will  show  the  relation  of  the  ore  body 
to  the  associated  formations.  It  will  be  seen  that  the  limestone  and 
greenstone  beds,  which  here  strike  N.  60°  W.  and  dip  30°  NE., 
are  cut  by  a fault  running  N.  50°  E.  and  dipping  vertically  or  high 
southeast.  This  fault  makes  an  offset  of  300  feet  in  the  limestone- 
greenstone  contact  and  has  produced  a vertical  displacement  of  the 
beds  amounting  to  150  feet.  The  course  that  it  follows  in  the  lime- 
stone or  in  the  greenstone  at  a distance  from  the  contact  is  difficult 


THE  NIZINA  DISTRICT,  ALASKA. 


94 


to  trace,  but  the  position  of  Nikolai  Creek  east  of  the  Nikolai  mine 
was  probably  determined  partly  by  the  fault,  as  was  also  the  de- 
pression between  the  small  knob  on  the  south  side  of  the  Nikolai  ore 
body  and  the  hill  slope  still  farther  south.  Open  spaces  between  the 
limestone  and  the  greenstone  along  the  fault  plane  were  filled  with 
masses  of  coarse  white  calcite.  This  filling,  however,  was  not  seen 
where  both  walls  of  the  fault  are  limestone  or  greenstone. 

The  main  Nikolai  vein  makes  a slight  angle  with  the  principal 
fault  and  lies  to  the  north  of  it.  It  strikes  N.  55°  E.  and  dips  70° 
SE.  The  ore  body  was  produced  by  deposition  and  replacement  in 
a shear  zone  in  the  greenstone  that  has  a width  ranging  on  the  sur- 


1000  500  0 

L-j...  t— i-  j I i 


1000 


2000  FEET 


LEGEND 


Kennicott 

formation 


Chitistone 

limestone 


+ -t-  + 

+ +■  " 

+ + + 

Nikolai 

greenstone 

Main  fault 

Copper  lode 

Shaft 


Figure  9. — Sketch  map  of  area  in  vicinity  of  Nikolai  mine. 


face  from  4 to  6 feet.  Deposition  of  copper  minerals  was  confined 
to  a part  of  the  shear  zone  that  has  a horizontal  extent  from  north- 
east to  southwest  of  150  feet,  but  the  shear  zone  itself  can  be  traced 
100  feet  farther  southwest  and  350  feet  farther  northeast,  making 
a total  exposure  of  GOO  feet. 

Several  open  cuts  were  made  on  the  vein  and  a shaft  was  sunk 
in  the  ore  body  near  its  northern  end  a few  feet  above  the  creek. 
Fifty  feet  south  of  the  shaft  two  open  cuts  expose  a second  fault 
zone  parallel  to  the  first,  along  which  copper  minerals  were  deposited. 
It  was  traced  for  a distance  of  50  feet  on  the  surface.  Moss  and  loose 
rock  hide  it  beyond  these  limits,  but  it  evidently  is  much  more  poorly 
developed  than  the  fault  zone  to  the  north. 


COPPER. 


95 


Another  set  of  fractures  or  joints,  with  strike  N.  15°  W.  and  dip 
70°  W.,  is  associated  with  the  northeast-southwest  faulting  but  does 
not  appear  to  have  resulted  in  any  important  displacement  or  to 
have  offered  favorable  channels  for  circulating  mineral  solutions, 
although  the  openings  near  the  main  vein  were  followed.  Still 
other  fractures  are  present  which  were  not  recognized  as  belonging 
to  any  definite  system. 

The  copper  minerals  that  form  the  Nikolai  ore  body  occur  parti}7 
as  a filling  in  preexisting  cavities  and  partly  as  a replacement  of 
greenstone  near  the  cavities.  The  principal  copper  mineral  is  chal- 
copyrite,  but  with  the  chalcopyrite  is  associated  considerable  bornite. 
Where  the  copper  minerals  were  deposited  in  cavities  they  are  asso- 
ciated with  other  minerals — calcite,  epidote,  and  quartz;  where  they 
replace  greenstone  the  other  minerals,  if  they  can  be  distinguished 
at  all,  are  less  in  evidence. 

Deposition  was  greatest  within  the  sheared  and  broken  rocks  of 
the  fault  zone,  doubtless  because  the  opportunity  for  circulation  was 
best  there.  The  greenstone  walls,  within  a foot  or  so  of  the  fault, 
are  sheeted  with  innumerable  tiny  parallel  fractures  now  filled  with 
chalcopyrite,  giving  the  rock  a banded  appearance.  Deposition, 
however,  was  not  confined  to  these  veinlets.  It  took  place  also  by 
replacement  of  the  rock  itself,  so  that  the  greenstone  between  the 
veinlets  is  impregnated  with  copper  sulphide.  Small  veins  from 
one-fourth  to  one-half  an  inch  thick  show  a banding  of  minerals  in 
places  and  give  a clue  to  the  order  in  which  the  minerals  were  depos- 
ited. The  greenstone  walls  are  covered  by  a multitude  of  small 
epidote  crystals,  with  occasional  crystals  of  quartz,  and  after  them 
calcite  was  deposited.  Grains  and  small  lumps  of  chalcopyrite  are 
scattered  through  both  calcite  and  epidote.  The  ore  taken  from  the 
shaft  consists  largely  of  chalcopyrite,  and  the  dump  shows  that  there 
is  considerable  calcite  and  quartz  associated  with  it.  Bornite  de- 
creases— a fact  that  is  taken  as  evidence  that  this  mineral  belongs  to 
the  upper  enriched  part  of  the  vein  and  that  the  ore  will  be  found 
to  consist  of  chalcopyrite  as  depth  is  gained.  There  has  been  some 
movement  along  the  fault  since  the  ore  was  deposited,  but  it  prob- 
ably has  not  produced  much  displacement. 

WESTOVER  CLAIM. 

The  Westover  claim,  which  is  owned  by  the  Alaska  United  Ex- 
ploration Company,  is  on  the  east  side  of  Bowlder  Creek,  a little  less 
than  2 miles  north  of  the  junction  of  Bowlder  and  Dan  creeks.  The 
discovery  outcrop  is  a mass  of  bornite  3,500  feet  above  the  flats  of 
Nizina  River  and  about  375  feet  above  the  glacier  moraine  of 
Bowlder  Creek  valley.  It  is  situated  at  the  contact  of  the  Chitistone 


96 


THE  NIZINA  DISTRICT,  ALASKA. 


limestone  and  the  Nikolai  greenstone,  but  the  ore  body  is,  so  far  as 
now  exposed,  in  the  limestone.  Most  of  the  limestone-greenstone 
contact  in  the  upper  end  of  Bowlder  Creek  valley  is  covered  by  talus 
from  the  high  limestone  cliffs  that  form  the  valley  walls,  yet  in  a 
few  places,  of  which  this  locality  is  one,  the  contact  is  exposed  for 
short  distances.  The  strike  of  the  limestone  beds  and  the  greenstone 
flows  is  here  N.  15°  W.  and  the  dip  is  15°  E.  In  half  a dozen  or  more 
places  within  the  valley  appear  small  faults  cutting  across  the  con- 
tact of  the  two  formations  and  causing  displacements  that  in  several 
instances  amount  to  a hundred  feet  or  more.  One  or  two  such  dis- 
placements took  place  a short  distance  south  of  the  Westover  ore 
body,  thus  bringing  the  greenstone  at  the  outcrop  to  a higher  posi- 
tion with,  reference  to  its  nearest  exposures  on  the  south  than  it 
would  have  otherwise  had.  Both  limestone  and  greenstone  near  the 
ore  body  are  broken  by  many  joints  and  crossed  by  slip  planes  of 
little  displacement.  Locally  the  rocks  are  much  shattered  and  break 
down  in  small  fragments.  One  of  the  most  prominent  of  the  frac- 
tures has  an  important  relation  to  the  ore  body.  It  is  a fault, 
probably  of  small  displacement,  whose  contact  surfaces  are  warped 
surfaces  rather  than  planes,  so  that  the  trace  of  the  fault  on  the 
ledge  is  a curved  line  sloping  from  right  to  left  as  one  looks  at  it. 
This  fault  strikes  west-northwest  and  dips  45°  NNE.  The  ore  body 
lies  on  the  north  or  upper  side  of  the  fault,  but  is  not  fully  exposed 
because  the  talus  has  been  but  partly  cleared  away  from  its  base 
and  the  actual  contact  of  limestone  and  greenstone  is  not  in  sight. 
Copper  ore  is  exposed  along  the  face  of  the  limestone  cliff  at  the  top 
of  the  talus  slope  for  a distance  of  35  feet  horizontally  and  at  the 
south  end  of  the  ore  body  for  a distance  of  about  10  feet  vertically. 
The  south  end  of  the  ore  body  is  rich  massive  bornite  and  clialcocite 
ore,  which  is  sharply  cut  off  from  the  limestone  south  of  it  by  the 
fault  and  has  been  formed  by  an  almost  complete  replacement  of 
limestone  by  the  copper  sulphides.  On  following  the  ore  body  north 
the  richness  of  the  ore  rapidly  decreases,  till  finally  bornite  disappears 
and  only  silicified  limestone  is  seen. 

The  copper-bearing  solutions  followed  all  the  available  openings 
in  the  limestone — joints,  bedding  planes,  and  faults — and  the  richest 
ore  is  near  such  openings,  for  here  the  lime  carbonate  was  wholly 
replaced  by  copper  sulphides.  The  amount  of  replacement  varies 
inversely  as  the  distance  from  these  openings  till,  within  a few 
inches  or  a foot,  the  grains  and  tiny  veinlets  of  bornite  can  no  longer 
be  seen  in  the  limestone.  Where  the  limestone  was  greatly  shattered 
the  opportunity  for  replacement  was  greater ; but  in  the  more  massive 
parts  of  the  beds  it  took  place  sparingly,  if  at  all. 

The  sharply  defined  contact  of  ore  and  limestone  at  the  fault  on 
the  south  suggests  that  the  displacement  is  later  than  the  ore  deposi- 


COPPER. 


97 


tion.  If  this  is  the  case,  the  present  exposure  does  not  show  a com- 
plete section  of  the  original  ore  body  and  further  prospecting  may 
reveal  the  displaced  part. 

OTHER  PROSPECTS. 

Tliere  has  probably  been  more  prospecting  for  copper  in  the  Nizina 
district  than  in  any  other  part  of  Chitina  Valley  except  the  vicinity 
of  Kotsina  River.  Prospecting  was  stimulated  by  the  discovery  of 
such  deposits  as  the  Bonanza,  the  Jumbo,  the  Nikolai,  and  other 
claims  and  by  the  presence  of  a greater  number  of  prospectors.  The 
limestone-greenstone  contact  has  been  examined  with  care  wherever 
it  is  accessible,  and  most  of  it  has  been  staked.  Most  of  the  copper 
found  is  of  the  class  of  disseminated  sulphides  in  greenstone.  Ex- 
amples of  this  class  are  found  in  the  Donohoe  prospects  in  the  green- 
stone on  the  east  side  of  McCarthy  Creek  and  the  prospects  of  the 
Alaska  United  Copper  Exploration  Company  on  the  west  side  of 
Bowlder  Creek,  opposite  the  Westover  claim,  and  on  the  east  side  of 
Bowlder  Creek  north  of  Dan  Creek.  The  copper  sulphides  of  the 
last-named  locality  occur  along  joint  or  fault  planes,  some  of  which 
are  nearly  parallel  with  the  major  strike  fault  of  the  Dan  Creek 
valley  and  some  cross  these  at  large  angles.  In  1909  a tunnel  was 
being  driven  on  the  property  about  one-fourth  of  a mile  east  of 
Bowlder  Creek  and  275  feet  below  the  limestone-greenstone  contact 
lo  cut  a fissure  carrying  copper  minerals  that  was  exposed  175  feet 
higher  to  the  north.  A belt  of  greenstone  with  disseminated  copper 
sulphides  is  found  at  about  this  distance  below  the  limestone  and 
extends  east  along  the  north  side  of  Dan  Creek  valley.  It  carries 
small  amounts  of  bornite  and  chalcopyrite,  and  in  places  a little 
native  copper  is  present.  The  native  copper  is  believed  to  be  a sec- 
ondary alteration  product  derived  from  the  sulphide.  Bowlders  of 
greenstone  earning  native  copper  are  not  unusual  in  the  gravels  of 
Dan  Creek.  Not  much  work  has  been  done  on  the  native  copper- 
bearing greenstone,  and  the  quantity  of  copper  there  is  not  yet  deter- 
mined. The  principal  prospects  of  this  kind  are  on  the  upper  part 
of  Dan  Creek  and  are  the  property  of  the  Dan  Creek  Gold  and 
Copper  Company. 

A small  deposit  of  copper  carbonates,  malachite,  and  azurite  is 
found  in  the  limestone  only  a few  feet  above  the  limestone-greenstone 
contact  south  of  Chitistone  River,  a mile  east  of  the  Nizina  River 
valley.  The  copper  minerals  were  deposited  in  a crushed  and  faulted 
part  of  the  limestone  and  the  whole  is  much  stained  with  iron  oxide. 
Two  short  prospecting  tunnels  were  driven  in  the  limestone  by  the 
Houghton  Alaska  Exploration  Company,  to  whom  the  prospect 
belongs. 

70648°— Bull.  448—11 


-7 


98 


THE  NIZINA  DISTRICT,  ALASKA. 


GOLD. 

PRODUCTION. 

All  the  gold  produced  in  the  Chitina  Valley  has  come  from  the 
placers  of  Dan,  Chititu,  and  Young  creeks.  Chititu  Creek  is  the 
principal  producer,  and  after  it  comes  Dan  Creek.  Young  Creek 
has  had  only  a small  output  up  to  the  present  time  and  may  almost 
be  disregarded  as  a contributor  in  past  years,  but  with  lower  freight 
rates  and  cheapened  cost  of  production  it  may  become  of  greater  im- 
portance in  the  future.  The  total  gold  production  of  Chititu  and 
Dan  creeks  from  1903  to  1909,  inclusive,  may  be  estimated  with  a 
considerable  degree  of  accuracy  as  between  $450,000  and  $500,000,  or 
an  average  of  about  $65,000  a year.  There  is  good  reason  to  believe 
that  with  the  installation  of  new  equipment  on  the  completion  of  the 
railroad  this  yearly  average  will  be  much  increased. 

SOURCE  OF  THE  GOLD. 

It  may  be  said  with  certainty  that  the  source  of  the  placer  gold  of 
Dan,  Chititu,  and  Young  creeks  is  in  the  black  shales  of  the  Kenni- 
cott  formation.  This  is  clearly  shown  by  the  distribution  of  the  gold 
itself.  All  the  tributaries  that  flow  into  Dan  and  Copper  creeks 
from  the  northeast,  including  Dan  Creek  above  the  mouth  of  Copper 
Creek,  lie  within  the  limestone-greenstone  area  and  carry  no  gold. 
All  the  tributaries  that  flow  into  Dan  and  Copper  creeks  from  the 
southwest  head  in  the  shale  area  and  all  carry  gold.  All  the  gravel 
deposits  of  Dan  and  Copper  creeks  except  a part  of  the  bench  and 
stream  gravels  on  lower  Dan  Creek  are  derived  from  sources  within 
the  drainage  basin  of  these  streams.  No  foreign  material  was  found, 
and  there  is  almost  no  possibility  that  any  could  be  present,  for  the 
whole  basin  is  surrounded  by  steep  walls  which  probably  never 
Avere  below  the  surface  of  the  ice  fields  during  the  time  of  greatest 
glaciation. 

All  the  tributaries  of  Chititu  Creek  originate  within  the  black 
shale  area  and  all  carry  gold,  but  here,  as  on  Young  Creek,  part  of 
the  gravels  are  of  foreign  origin  brought  in  by  glacial  transportation. 
Rex  Creek  is  the  one  exception  to  this  statement,  for  its  gravels,  save 
in  the  lower  mile  of  its  course,  are  all  derived  from  within  its  own 
drainage  basin.  The  gravels  of  the  upper  Rex  Creek  valley  are 
derived  from  the  black-shale  area  and  carry  gold.  No  evidence  was 
obtained  to  indicate  any  other  source  for  the  gold  of  Chititu  and 
Dan  creeks  than  the  shales  lying  between  Dan  and  Young  creeks, 
although  all  the  copper  and  probably  all  or  nearly  all  the  silver  of 
Chititu  Creek  came  from  an  outside  source. 

Many  small  quartz  veins  carrying  pyrite  and  native  gold  have  been 
found  in  the  black  Kennicott  shales  between  Copper  and  Rex  creeks. 


GOLD. 


99 


They  range  in  thickness  from  less  than  an  inch  to  several  inches  and 
are  believed  to  have  a close  relation  to  the  porphyritic  intrusions  in 
the  shales.  Molybdenite  is  present  and  stibnite  is  also  reported 
from  these  veins.  The  placer  gravels  contain,  besides  the  metals 
gold,  silver,  and  copper,  such  heavy  minerals  as  galena,  cinnabar, 
barite,  pyrite,  and  possibly  marcasite.  Native  lead  with  a white 
coating,  thought  to  be  cerusite,  was  found  in  the  sluice  boxes  on 
Chititu  Creek,  but  may  have  been  introduced  by  white  men  or 
natives,  for  bullets  and  shot  are  common.  Not  all  of  these  minerals 
have  been  found  in  place  in  the  rock,  but  it  is  probable  that  they 
also  are  associated  with  the  quartz  veins  and  porphyry  intrusions. 
Thin  veins  no  thicker  than  a sheet  of  paper  are  common  in  joint 
planes  of  the  hard  argillite  bowlders  in  the  stream  gravels.  They 
contain  quartz,  pyrite,  and  in  places  free  gold.  A thin  vein  less 
than  one-fourth  of  an  inch  thick  was  found  in  a porphyry  dike  on 
the  upper  part  of  Rex  Creek,  which  consisted  of  quartz  with  molyb- 
denite and  pyrite  and  assayed  0.18  ounce  gold  and  12.80  ounces 
silver  to  the  ton.  The  dike  rock  near  the  vein,  although  seemingly 
little  altered,  contained  pyrite  and  showed  a trace  of  both  gold  and 
silver.  There  is  thus  good  evidence  for  the  source  of  the  gold  aside 
from  that  furnished  by  its  distribution  in  the  gravels. 

The  gold  in  the  stream  gravels  is  in  part  a concentration  from 
the  bench  gravels  through  which  the  streams  have  cut  their  chan- 
nels and  in  part  a concentration  from  the  products  of  weathering 
derived  directly  from  the  shales  and  the  auriferous  veins.  Probably 
the  greater  part  is  a reconcentration  from  the  older  deposits.  Ex- 
tensive accumulations  of  high  bench  gravels  are  present  on  both 
Dan  and  Chititu  creeks.  They  are  best  developed  on  the  lower 
parts  of  the  streams  but  extend  into  some  of  the  tributary  valleys. 
The  bench  gravels  of  Dan  Creek  extend  west  from  the  neighborhood 
of  Copper  Creek  and  around  to  the  west  slope  of  Williams  Peak,® 
where  they  reach  an  elevation  of  over  1,200  feet  above  the  flats  of 
Nizina  River.  The  bench  gravels  of  Chititu  Creek  reach  an  eleva- 
tion as  great  as  or  greater  than  those  of  Dan  Creek.  In  both  places 
they  represent  a filling  in  old  valleys  through  which  the  present 
streams  have  cut  their  channels  and  in  so  doing  have  reconcentrated 
a great  volume  of  older  deposits,  derived  partly  from  the  upper 
Nizina  Valley  and  the  region  east  of  the  heads  of  White  and  Young 
creeks  but  chiefly  from  the  drainage  basin  of  Dan  and  Chititu 
creeks.  When  the  bench  gravels  were  laid  down  the  two  great 
ice  streams  that  came  down  the  Nizina  and  Chitina  valleys  were 
still  in  existence,  although  on  the  retreat.  They  formed  the  bar- 
rier behind  which  it  was  possible  for  such  deposits  to  accumulate 

a Williams  Peak  is  named  in  honor  of  John  M.  Williams,  a pioneer  prospector  of  the 
Nizina  district,  who  was  killed  in  a snowslide  on  Bonanza  Creek  on  April  7,  1909. 


100 


THE  NIZINA  DISTRICT,  ALASKA. 


and  brought  to  the  bench  gravels  that  part  of  them  which  is  foreign 
to  Dan  and  Chititu  creeks.  It  is  impossible  to  say  what  proportion 
of  the  gravels  consists  of  foreign  material,  but  it  is  believed  to  be  the 
smaller  part.  Some  of  the  bench  gravels  carry  gold  in  sufficient 
quantity  to  be  of  commercial  importance,  as  has  been  proved  at  a 
number  of  places.  A reconcentration  of  such  deposits  accounts  in  part 
for  the  greater  richness  of  the  stream  gravels.  The  process  that 
brought  about  this  concentration  is  exactly  the  same  in  principle  as 
that  carried  on  in  the  miners’  sluice  boxes  on  a much  smaller  scale  but 
in  a much  shorter  time.  This  concentration  is  probably  slower  at 
present  than  it  was  before  the  streams  had  cut  through  the  deep 
gravel  accumulations  and  intrenched  themselves  in  the  underlying 
hard  rock,  but  it  still  goes  on,  for  erosion  of  the  bench  gravels  has 
not  ended. 

PLACER  DEPOSITS. 

DAN  CREEK. 

Dan  and  Copper  creeks  may  well  be  regarded  as  one  stream  in 
spite  of  whatever  accident  or  design  resulted  in  their  having  dif- 
ferent names  and  of  the  fact  that  the  upper  part  of  Dan  Creek  some- 
times carries  as  much  or  more  water  than  Copper  Creek.  A refer- 
ence to  the  geologic  map  (PL  III,  in  pocket)  will  show  that  the 
two  streams  follow  closely  the  course  of  the  fault  that  gave  the 
older  greenstone  and  the  limestone  on  the  north  their  relative  ele- 
vation above  the  base  of  the  Kennicott  formation.  With  unimpor- 
tant exceptions,  the  north  side  of  the  Dan  and  Copper  creek  val- 
leys is  in  limestone  and  greenstone,  the  south  side  in  shales  of  the 
Kennicott  formation.  Most  of  Copper  Creek  is  in  a broad  glaci- 
ated valley,  but  at  a point  nearly  1 mile  above  its  mouth  the  creek 
enters  a narrow  rock-walled  canyon  that  opens  slightly  below  Cop- 
per Creek  yet  extends  down  Dan  Creek  nearly  a mile.  Dan  Creek 
valley  below  the  canyon  is  narrow  and  shut  in  by  steep  mountains 
as  far  as  the  flats  of  Nizina  River. 

During  the  ice  invasion  the  Copper  Creek  valley  was  swept  clear 
of  whatever  unconsolidated  deposits  may  have  accumulated,  and 
the  form  of  the  valley  was  considerably  modified.  When  the  ice 
was  retreating  some  glacial  debris  was  left  on  the  valley  floor,  but  it 
is  of  less  importance  in  connection  with  the  gold  placers  than  the 
accumulations  of  stream  gravels  that  have  been  laid  down  since  the 
glacier  disappeared.  In  this  respect  the  placers  of  Copper  Creek 
are  different  from  those  of  Dan  Creek. 

All  the  tributaries  of  Copper  Creek  on  its  south  side,  as  Idaho, 
Rader,  and  Seattle  gulches,  carry  gold,  but  most  of  the  output  of 
the  creek  comes  from  near  the  mouth  of  Rader  Gulch.  Part  of  the 
gold  is  from  the  gulch  itself  and  part  is  from  Copper  Creek,  just 


GOLD. 


101 


below  the  gulch.  The  gravels  are  all  shallow.  Those  in  the  mouths 
of  the  gulches  are  composed  almost  entirely  of  shale,  chiefly  from 
the  Kennicott  formation  but  also  in  part  from  the  McCarthy  shale. 
They  occupy  narrow  gulches  and  accumulate  so  rapidly  that  the 
streams  have  difficulty  in  removing  them.  The  gravel  deposits  of 
Rader  Gulch  are  of  this  character.  They  consist  of  loose  shale 
fragments  and  occupy  only  a few  hundred  feet  of  the  lower  end 
of  the  gulch,  for  above  them  the  grade  is  so  high  and  the  channel  so 
narrow  that  the  water  removes  loose  material  rapidly.  The  gravels 
of  the  main  stream  contain  material  from  all  the  formations  within 
the  drainage  basin.  At  Rader  Gulch  they  form  a narrow  flood-plain 
area  between  the  mountain  slope  on  the  southwest  and  a low  ridge  on 
the  northeast.  They  contain  considerable  coarse  material  mingled 
with  blocks  and  bowlders  of  glacial  origin  and  much  fine  material 
derived  from  the  shales.  The  gold  is  not  a concentration  from  older, 
lower-grade  deposits  but  is  derived  directly  by  weathering  and  by 
stream  concentration  of  the  products  of  weathering.  The  source  of 
most  of  the  gold  is  clearly  indicated  by  its  position  in  the  gravels 
at  and  just  below  the  mouth  of  Rader  Gulch  and  the  presence  of 
workable  gravels  on  the  lower  part  of  Rader  Gulch. 

Idaho  and  Seattle  gulches  resemble  Rader  Gulch  in  their  form  and 
the  character  of  their  gravel  deposits,  but  they  have  not  been  found 
to  carry  as  much  gold. 

Copper  Creek  is  difficult  to  reach  with  supplies  except  in  winter, 
for  the  canyon  makes  necessary  a high  climb  of  more  than  1,000  feet 
around  the  side  of  Williams  Peak.  Men  on  foot,  however,  can  fol- 
low the  creek.  Logs  have  been  placed  across  the  stream  in  the  can- 
yon and  make  it  possible  to  avoid  bad  places.  Mining  on  Copper 
Creek  is  done  with  pick  and  shovel.  There  is  a small  supply  of 
timber  for  firewood  and  for  sluice  boxes,  but  it  would  not  be  ade- 
quate for  extensive  mining  operations.  Good  timber  for  lumber  can 
be  secured  along  Nizina  River,  but  the  expense  of  carrying  it  to 
Copper  Creek  under  present  conditions,  except  in  winter,  would  be 
great. 

The  gold  of  Dan  Creek  has  a less  simple  history  than  that  of  Cop- 
per Creek.  It  is  in  part  a reconcentration  from  older  gold-bearing 
bench  gravels  and  in  part,  like  that  of  Copper  Creek,  a concentration 
from  the  products  of  later  erosion.  Old  high-bench  gravels  are 
found  on  both  sides  of  Dan  Creek,  especially  on  the  lower  part,  but 
near  the  west  end  of  the  canyon  they  lose  their  prominence  and  dis- 
appear altogether  at  or  below  the  mouth  of  Copper  Creek.  Dan 
Creek  has  cut  its  present  channel  down  through  this  great  accumu- 
lation of  glacial  and  stream  deposits  and  into  the  shales  beneath. 
The  stream  gravels  consist  of  greenstone,  limestone,  and  shale.  They 
form  between  rock  walls  a narrow  flood  plain  overgrown  with  timber 


102 


THE  NIZINA  DISTRICT,  ALASKA. 


and  in  many  places  of  less  width  than  a placer  claim.  A large  part 
of  the  gravels  consists  of  bowlders  ranging  from  cobbles  to  masses 
several  feet  in  diameter.  Most  of  them,  however,  are  not  too  large 
to  be  moved  by  hand.  All  the  fragments  are  rounded.  They  were 
deposited  by  a rapidly  flowing  current  and  the  bedding  is  poor. 
Buried  spruce  logs  and  fragments  of  wood  are  common.  The  gravel 
and  its  slight  covering  of  soil  range  from  8 to  12  feet  in  depth. 

Dan  Creek  gold  is  coarse  and  smooth  and  is  accompanied  by  silver 
and  copper.  It  has  been  concentrated  on  bed  rock  or  within  the 
lower  2 feet  of  the  gravel.  A large  proportion,  however,  finds  its 
way  into  the  cracks  and  crevices  in  the  shale,  so  that  in  places  a foot 
or  more  of  the  shale  has  to  be  removed  to  recover  all  the  metal.  An 
unusual  feature  of  the  gravels  of  Dan  Creek  is  the  small  quantity  of 
fine  gold  found  in  them.  Very  little  fine  gold  is  recovered  in  the 
sluice  boxes  and  practically  none  is  found  in  panning.  Numerous 
prospect  holes  show  that  the  gold  is  well  distributed  across  the  chan- 
nel and  have  failed  to  discover  the  presence  of  a concentration  into  a 
defined  pay  streak.  Beside  the  holes  sunk  on  the  flood  plain,  tunnels 
have  been  driven  along  bed  rock  at  the  base  of  the  bench  gravels 
above  the  present  flood  plain.  The  depth  to  which  the  creek  has 
incised  itself  in  the  shales  is  not  constant  but  is  rarely  less  than  10 
or  15  feet.  Thus  the  base  of  the  bench  gravels  or  the  “ rim  ” of  the 
channel  stands  well  above  the  creek.  The  tunnels  driven  in  the 
bench  gravels  show  the  presence  of  gold  in  sufficient  amount  to  be  of 
commercial  importance  and  in  several  places  in  sufficient  amount  to 
pay  for  extraction  under  the  expensive  methods  necessary  in  pros- 
pecting the  gravels,  but  the  final  test  of  value  will  come  when  an 
attempt  is  made  to  extract  the  gold  on  a large  scale. 

An  old  channel  formerly  occupied  by  Dan  Creek  lies  in  the  bench 
gravels  on  the  south  side  of  the  present  stream.  It  runs  on  the  south 
side  of  the  small  round  hill  west  of  the  mouth  of  Copper  Creek  and 
follows  the  hillside  to  the  west,  but  it  has  not  been  traced  definitely. 
Doubtless  much  of  it  has  been  removed  by  erosion.  Its  gravels  carry 
gold,  and  an  attempt  has  been  made  to  exploit  them  in  a small  way, 
but  without  great  success. 

Dan  Creek  is  favorably  situated  with  reference  to  timber  for 
mining  purposes  and  has  a good  supply  of  water.  It  is  reached 
without  any  difficulty  from  the  Nizina,  and  a wagon  road  for  hauling 
timber  and  supplies  has  already  been  built.  All  mining  to  the  present 
time  has  been  by  the  simplest  methods.  The  one  employed  for  several 
years  is  to  undercut  the  bank  with  a stream  of  water  and  by  washing 
away  the  gravel  to  leave  the  gold.  Bowlders  and  small  rocks  are 
piled  parallel  with  the  bank  and  only  a few  feet  from  it.  Then  wafer 
controlled  by  dam  and  gates  is  turned  in  and  forced  against  the  bank, 
undercutting  it  and  carrying  away  most  of  the  fine  gravel.  The  large 


GOLD. 


103 


rocks  are  piled  back  by  hand  and  the  remaining  fine  gravel  and  gold 
are  shoveled  into  sluice  boxes,  after  which  bed  rock  is  cleaned.  Prep- 
aration has  been  made  for  installing  a hydraulic  plant  on  Dan  Creek, 
and  it  will  be  put  in  place  as  soon  as  the  railroad  is  completed  and 
better  facilities  for  carrying  freight  are  established. 

CHITITU  CREEK. 

Chititu  Creek  and  its  two  branches,  Rex  and  White  creeks,  lie 
wholly  within  the  area  of  Kennicott  sediments.  These  streams,  like 
Dan  Creek,  have  cut  their  present  channels  through  the  old  valley 
filling  and  entrenched  themselves  in  the  black  shales.  The  amount 
of  this  entrenchment  is  variable,  ranging  from  nothing  below  the 
canyon  on  Chititu  Creek  to  60  or  TO  feet  on  White  Creek,  but  the 
increase  is  not  uniform.  It  is  about  30  feet  at  the  mouth  of  White 
Creek,  but  is  greater  than  that  in  places  farther  down  on  Chititu 
Creek.  It  decreases  as  Rex  Creek  is  ascended  and  also  on  the  head  of 
White  Creek.  The  canyon  on  Chititu  Creek  is  due  to  the  presence  of 
a large  porphyry  dike  in  the  black  shales,  which  has  protected  them 
from  rapid  stream  cutting  and  confined  the  water  to  a narrow  chan- 
nel. The  canyon  is  small  but  marks  the  downstream  limit  of  gold- 
bearing  gravels  that  are  now  considered  of  commercial  importance. 

Above  the  rim  of  the  shallow  trench  cut  in  the  shales  by  the  stream 
are  steep  banks  of  rudely  assorted  gravels.  The  top  of  the  gravel 
bluff  at  Sunday  Gulch  is  a little  more  than  500  feet  above  Chititu 
Creek.  Half  a mile  downstream  the  top  of  the  bluff  is  750  feet 
above  the  creek,  but  from  this  point  on  the  difference  grows  smaller 
till  the  bench  gravels  merge  into  the  gravels  of  Nizina  Valley  a 
short  distance  below  the  canyon.  Bench  gravels  are  prominent  on 
Rex  Creek  for  a mile  or  more  above  its  mouth,  but  they  either  were 
not  deposited  or  have  been  removed  from  the  upper  end  of  the  creek, 
where  the  unconsolidated  accumulations  are  wholly  glacial  debris. 
A large  part  of  the  bench  deposits  of  White  Creek  have  been  eroded 
away,  yet  they  extend  up  the  creek  in  conspicuous  exposures  for  at 
least  2 miles. 

The  richest  gold-producing  gravels  of  Chititu  Creek  are  the  stream 
gravels ; they  include  all  of  Chititu  Creek  above  the  canyon,  together 
with  a large  part  of  Rex  and  White  creeks.  The  most  important 
parts  of  these  creeks,  viewed  from  the  standpoint  of  gold  production, 
are  represented  on  the  sketch  map  (fig.  10).  The  stream  gravels 
cover  the  floor  of  the  shallow  rock-rimmed  trench  to  a depth  of 
8 to  16  feet,  depending  partly  on  the  form  of  the  bed-rock  surface 
and  partly  on  the  irregularities  of  deposition  by  a swiftly  flowing 
current.  They  form  a flat,  originally  covered  with  timber  and  under- 
brush, ranging  in  width  from  200  to  700  feet.  The  gravels  of  Chititu 
and  White  creeks  and  of  the  lower  part  of  Red  Creek  consist  of 


104 


THE  NIZINA  DISTRICT,  ALASKA. 


shale,  limestone,  sandstone,  and  quartz  diorite  porphyry,  all  of  local 
origin,  mingled  with  greenstone,  diorite,  and  other  rocks  brought  in 
by  glacial  ice  from  a foreign  source.  Shale,  sandstone,  and  porphyry 
make  up  the  fragmental  deposits  of  the  upper  part  of  Rex  Creek. 


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Bowlders  and  large  blocks  make  up  a considerable  portion  of  the 
gravel  deposits,  but  not  so  large  a proportion  as  on  Dan  Creek. 
Some  of  the  glacial  erratics  are  6 or  8 feet  in  diameter.  Most  of 
the  bowlders,  however,  can  be  sent  through  the  sluice  boxes,  although 
it  is  necessary  to  break  part  of  them  with  powder. 


of  bench  and  stream  gravels. 


GOLD. 


105 


The  gravels  producing  gold  at  present  include  those  of  Chititu 
Creek  and  of  the  lower  part  of  Rex  Creek.  Very  little  work  aside 
from  that  necessary  to  hold  the  claims  has  been  done  on  White  Creek 
for  several  years.  In  a general  way  the  gold  of  Chititu  Creek  is  dis- 
tributed through  the  gravel  from  rim  to  rim  of  the  rock  channel, 
but  it  was  found  that  at  one  place  near  the  canyon  there  is  a very 
well-defined  pay  streak,  such  as  had  not  been  found  before  on  any 
of  the  claims  farther  up  the  creek.  Most  of  the  gold  is  on  or  near 
bed  rock.  Very  little  of  it  is  found  in  the  upper  part  of  the  gravel. 
The  gold  penetrates  the  bed  rock  through  cracks  and  all  openings, 
so  that  it  is  necessary  to  clean  the  rock  carefully  by  hand  after  taking 
up  the  loose  upper  part  to  the  depth  of  a foot  or  more.  There  are 
considerable  differences  in  the  character  of  the  bed-rock  surface, 
owing  to  irregularities  in  form  and  differences  of  hardness.  In 
places  the  old  stream  has  worn  the  rock  smooth  or  has  hollowed  out 
cavities  and  depressions.  Differences  in  the  depth  of  weathering  also 
add  to  the  irregularities  of  the  exposed  surface,  for  the  streams  of 
water  from  the  hydraulic  giants  cut  away  the  loose  rock  and  leave 
the  harder  parts  standing  in  relief.  Without  doubt  much  of  the 
gold  of  Chititu,  Rex,  and  White  creeks  is  a concentrated  product 
from  the  bench  gravels  and  the  remainder  is  derived  directly  by 
weathering  from  the  surrounding  shales.  All  the  bench  gravels  carrj 
gold  in  some  amount,  and  with  decreased  cost  of  mining  it  is  prob- 
able that  some  of  them  will  be  exploited. 

Chititu  gold  is  finer  and  less  worn  than  that  of  Dan  Creek.  It 
was  found  on  the  lower  part  of  Chititu  Creek  that  in  a set  of  4 
screens  ranging  from  10  to  20  mesh  about  equal  amounts  of  gold, 
by  weight,  were  caught  in  each  screen;  at  the  mouth  of  Rex  Creek 
it  was  estimated  that  from  25  to  40  per  cent  of  the  gold  passes 
through  a 16-mesh  sieve.  These  results  are  in  marked  contrast  with 
the  heavy  coarse  gold  of  Dan  Creek,  yet  both  come  from  the  same 
area  of  mineralization.  There  is,  nevertheless,  a little  coarse  gold  on 
Chititu  Creek,  and  several  large  nuggets  have  been  found.  The 
gold  assays  about  $18.70  per  ounce  when  cleaned.  A large  quantity 
of  copper  is  obtained  in  the  clean-up,  and  nuggets  of  native  silver 
are  common.  Several  other  heavy  minerals  besides  copper  and  silver 
are  caught  in  the  sluice  boxes,  such  as  pyrite,  galena,  stibnite,  barite, 
and  lead.  Most  of  the  lead  wTas  evidently  introduced  through  the 
use  of  firearms,  but  some  of  the  pieces  examined  did  not  resemble 
the  battered  bullets  found  in  the  sluice  boxes  and  had  a thick  white 
coating  of  oxidized  material.  One  of  the  largest  of  the  native-silver 
nuggets  was  found  in  1909 ; it  weighed  over  7 pounds  but  contained 
considerable  quartz. 

Native  copper  is  a source  of  considerable  difficulty  and  expense  in 
mining.  Several  hundred  pounds  of  fine  copper  are  secured  at  every 


106 


THE  HIZINA  DISTRICT,  ALASKA. 


clean  up  and  many  large  masses  are  taken  from  the  cuts.  Occasion- 
ally a large  piece  goes  through  the  boxes  and  into  the  dump,  but  the 
largest  are  too  heavy  to  be  driven  out  of  the  cut  by  the  giant.  All 
the  gold  is  picked  over  by  hand  to  remove  the  fine  copper  not  sepa- 
rated in  the  sluice  box.  During  the  early  days  of  mining  no  effort 
was  made  to  save  the  copper,  since  the  expense  of  carrying  it  to  the 
coast  was  greater  than  its  value,  yet  with  railroad  transportation  it 
should  now  be  worth  considering. 

For  the  first  few  years  after  the  discovery  of  gold  on  Chititu  Creek 
mining  was  conducted  on  Rex  and  White  creeks  as  well  as  on  Chititu 
Creek.  Rich  ground  was  found  on  all  these  streams,  and  the  prin- 
cipal operations  were  on  the  upper  half  of  Chititu  Creek,  the  lower 
end  of  Rex  Creek,  and  the  upper  part  of  White  Creek.  All  the  work 
was  done  by  hand  and  attention  was  directed  to  the  richest  ground 
only.  At  present  two  hydraulic  plants  are  in  operation,  one  on 
Chititu  Creek  and  the  other  at  the  mouth  of  Rex  Creek.  Most  of 
the  claims  on  Chititu  Creek  are  owned  by  the  Nizina  Mines  Com- 
pany and  a complete  hydraulic  plant  has  been  installed  to  exploit 


Figure  11. — Diagram  showing  the  method  of  operating  hydraulic  giants  on  Chititu  Creek. 


them.  This  plant  includes  flumes,  pipe  lines,  and  giants,  as  well  as  a 
complete  sawmill  and  an  electric  lighting  system.  The  sawmill  is 
equipped  with  planers  and  machinery  for  turning  out  standardized 
parts  of  flume  and  sluice  boxes  and  riffle  blocks  and  for  putting  them 
together.  There  is  also  a blacksmith  shop  and  equipment  for  han- 
dling iron  pipe.  A very  unusual  feature  for  an  Alaska  placer  mine  is 
the  complete  system  of  accounting  by  which  all  expenses  are  charged 
in  their  proper  place  and  the  cost  of  any  part  of  the  operations  is 
made  known. 

The  method  of  handling  gravel  in  the  pit  is  shown  in  figure  11. 
When  the  sluice  boxes  have  been  put  in  place  a bed-rock  flume  is 
carried  upstream  in  the  gravels  as  far  as  desired.  Then  the  upper 
end  of  this  cut  is  widened  to  100  or  150  feet  and  a giant  is  placed  on 
either  side  so  as  to  drive  the  gravel  along  the  sloping  face  into  the 
head  of  the  flume.  By  this  method  the  force  of  the  giants  is  added 
to  the  ground  sluice  water  and  a decided  gain  in  efficiency  is  ob- 
tained over  the  former  method  of  working  against  the  face  with  the 
giants  turned  upstream  and  away  from  the  sluice  boxes.  In  practice 


GOLD. 


107 


only  one  giant  is  used  at  a time,  the  opportunity  thus  being  given 
for  a gang  of  men  to  remove  the  large  bowlders  on  the  opposite  side. 
A giant  is  also  required  at  the  lower  end  of  the  sluice  boxes  to  stack 
the  tailings  and  keep  the  end  of  the  boxes  clear. 

Mining  operations  at  the  mouth  of  Rex  Creek  have  been  con- 
ducted by  Frank  Keman  with  a smaller  plant  than  that  on  Chititu 
Creek,  bur  they  have  been  carried  on  for  a longer  time.  A small 
giant  is  used  and  water  is  brought  from  Rex  Creek  in  a flume. 
The  conditions  here  are  about  the  same  as  on  Chititu  Creek,  but  the 
width  of  gravel  between  the  rock  rims  is  less.  Some  very  rich  ground 
has  been  found  on  the  lower  end  of  Rex  Creek  and  just  below  that 
on  Chititu  Creek. 

The  canyon  of  Chititu  Creek  is  4-J  miles  from  the  flats  of  Nizina 
River,  and  the  character  of  the  country  is  such  that  a good  wagon 
road  could  be  constructed  at  moderate  expense.  Such  a road  in  con- 
nection with  a bridge  over  the  Nizina  River  would  make  communi- 
cation with  the  railroad  at  Kennicott  River  easy  and  would  be  of 
great  advantage  to  the  miners  of  Chititu  Creek,  since  it  would  enable 
them  to  secure  supplies  at  any  time  of  the  year  at  a reasonable  cost. 
It  would  also  do  much  to  solve  the  problem  of  securing  labor  at  the 
time  when  it  is  most  needed  and  thus  prevent  the  necessity  of  carry- 
ing a large  force  of  men  on  the  pay  roll  during  the  whole  season. 
Labor  is  a large  item  in  the  expense  of  operation  at  present  chiefly 
because  of  the  large  amount  of  time  spent  in  winter  freighting. 
Wages  range  from  $90  per  month  and  board  bo  $5  per  day,  with  an 
additional  amount  to  foremen. 

Chititu  Creek  has  a sufficient  volume  of  water  for  all  the  demands 
that  are  made  on  it  by  the  hydraulic  plant  in  operation.  The  supply 
on  Rex  and  White  creeks  is  naturally  less  and  probably  would  be 
inadequate  for  a large  plant  at  some  seasons  of  the  year.  Chititu 
Creek  has  a fall  of  180  feet  per  mile  from  the  forks  to  the  canyon. 
Rex  and  White  creeks  have  a fall  of  250  feet  per  mile  in  the  lower 
2 miles  of  their  courses.  Thus  a good  head  of  water  can  be  secured 
on  each  of  these  streams.  There  is  an  abundance  of  good  timber 
for  lumber  and  mining  purposes  on  Chititu  Creek  below  the  canyon. 

YOUNG  CREEK. 

Young  Creek  resembles  Dan  and  Chititu  creeks  in  having  cut  its 
channel  through  an  old  gravel  filling  in  a glaciated  valley.  The 
present  stream  flows  in  a trench  cut  in  black  shales  and  lies  from 
20  to  40  feet  below  the  base  of  the  bench  gravels.  Its  channel  is  in 
reality  a shallow  canyon  whose  walls  are  shale  at  the  base  and  gravel 
above.  Young  Creek  valley  was  once  occupied  by  a glacier  which 
came  into  it  across  a broad  low  divide  near  its  head  and  was  an  over- 
flow branch  of  the  great  Nizina  Glacier.  The  gravels  of  Young  Creek 


108 


THE  NIZINA  DISTRICT,  ALASKA. 


therefore  contain  a large  amount  of  foreign  material  from  the  upper 
Chitina  Valley  in  addition  to  rocks  of  the  Kennicott  formation  and 
the  greenstone  from  its  own  valley. 

A large  part  of  the  creek  has  been  staked  for  placer  gold,  although 
the  production  has  not  }7et  been  enough  to  give  much  encouragement 
for  mining.  Two  men  were  prospecting  on  the  lower  part  of  the 
stream  in  1909.  In  previous  years  work  was  done  on  Calamity 
Gulch  also,  but  the  results  were  not  sufficiently  favorable  to  lead  to 
its  continuation. 

Young  Creek  carries  a large  stream  of  water  at  all  seasons  of  the 
year  and  has  an  average  fall  of  100  feet  per  mile  above  the  Nizina 
flats.  It  is  difficult  to  reach  the  upper  part  of  the  creek  because  of 
the  canyon-like  character  of  the  stream  channel  and  of  the  absence 
of  trails  above  the  creek  on  the  hill  slopes,  and  for  this  reason  it  is 
customary  to  cross  the  ridge  from  the  head  of  White  Creek  and  come 
down  on  Young  Creek  at  the  head  of  Calamity  Gulch.  This  is  the 
route  always  followed  by  prospectors  bound  for  the  head  of  Young 
Creek. 


INDEX. 


A.  Page. 

Alaska,  northern,  rocks  of,  correlation  of 26-27 

Alaska,  southeastern,  rocks  of,  correlation  of.  26-27 

Alaska  Peninsula,  rocks  of 42 

rocks  of,  correlation  of 26-27 

Alaska  Range,  rocks  of,  correlation  of 26-27 

Alaska  United  Copper  Exploration  Co.,  pros- 
pects of 97 

Amazon  Creek,  rock  glacier  on 58 

Azurite,  occurrence  of 79 

B. 

Bibliography  of  area 13 

Birch,  Stephen,  weather  observations  by : . . . 13 

Blei  Gulch,  rocks  on 34-35,36 

Bonanza  Creek,  fossils  from 24 

rocks  on 62 

Bonanza  Extension  Claim,  description  of 92 

Bonanza  mine,  copper  from 76,80 

description  of 84-90 

discovery  of 76 

faults  at 69-70,85 

map  of 87 

ores  of 86-90 

section  of,  figures  showing 88,89 

rock  glacier  near 58 

view  of 58 

rocks  at 62, 84-85 

view  of 84 

workings  at 84,87-88 

Bornite,  occurrence  of 78-79,82 

Bowlder  Creek,  copper  on 97 

Brooks,  A.  H.,  preface  by 7-8 

C. 

Calamity  Gulch,  rocks  near 35 

Canyon  Creek,  rocks  on 71 

Capps,  S.  R.,  work  of 13 

Chalcocite,  occurrence  of . 78-79 

Chalcopyrite,  occurrence  of 78-79,82 

Chinitna  Bay,  rocks  near 42 

Chitina  Glacier,  description  of 45-46,48 

Chitina  region,  copper  of,  survey  of 7 

Chitina  River,  description  of 9 

valley  of,  climate  of 14 

copper  of 77-80 

formation  of 74-75 

glaciation  in 45-46 

map  of Pocket. 

rocks  in 25,30,32,34,37.43,62,71 

Chitistone  limestone,  age  of 23-27 

character  of 11, 19, 20, 21-27 

copper  in 78-79 

deposition  of 72 

distribu"'  ion  of *. 22-23, 70 

fossils  o 24-25 


Page. 

Chitistone  River,  copper  on 80 

description  of 10 

fan  of 51 

fossils  from 24-25 

rocks  on  and  near 22, 61-62, 73 

Chititu  Creek,  copper  on 79-80 

description  of 10,20 

fan 51 

fossils  on 39 

glaciation  on , . . . 46, 47, 48, 49 

gold  on 76,98,103-107 

gravels  of 99-100 

hydraulicking  on,  figure  showing 106 

map  of,  showing  placers 104 

rocks  on  and  near 36, 37, 60, 103 

Chitty  Creek,  fossils  from 38 

Climate,  character  of 13-15 

Coal,  occurrence  of 73-74 

Columnar  section,  figure  showing 11 

Cook  Inlet  region,  rocks  of 42-43 

rocks  of,  correlation  of 25,26-27 

Copper,  discovery  of 75 

occurrence  of 75-76, 105-106 

mode  of 8,77-81 

production  of 76 

source  of 81-83 

Copper  Creek,  fault  on 68 

fossils  from 30,36,40 

glaciation  on 48 

gold  on 100-101 

rock  lenses  on,  figure  showing 65 

rocks  on  and  near 9, 34, 37-38, 66, 100 

view  of 18 

Copper  properties,  description  of 83-97 

groups  of 83 

Copper  River,  basin  of,  descriptiqp  of 14 

basin  of,  map  of 9 

rocks  in 73-74 

climate  of 14-15 

Correlations,  table  of 25-27 

Covellite,  occurrence  of 79 

Cretaceous  rocks,  correlation  of 26 

Cross,  W.,  and  Howe,  E.,  cited 54-55 

D. 

Dan  Creek,  copper  on 79-80, 83, 97 

description  of 10 

fan  on 51 

fault  on 68-69 

fossils  from 30, 40 

glaciation  on 46 

gold  on 76,98,100-103 

gravels  on 49, 99-100 

rocks  on  and  near 22, 

23, 29, 34, 36, 37-38, 61, 62, 66, 100 
Diorite.  See  Quartz  diorite. 

Donohoe  prospects,  location  of 97 

Drainage,  description  of 9-10,20 


109 


110 


INDEX. 


E.  Page 

Eagle  Creek,  rocks  on 34 

Economic  geology,  description  of 75-108 

Elevations,  altitude  of 10,18 

Elliott  Creek,  rocks  on 23 

Enochkin  formation,  correlation  of 26 

description  of 26,42 

Erie  claim,  description  of 91-92 

Erosion,  effects  of 51-52, 72 

Explorations,  description  of 12-13 

F. 

Falkland  Islands,  rock  streams  in 54 

Faulting,  occurrence  and  character  of 12, 68 

Field  work,  extent  of 13 

Fissure  veins,  occurrence  of 77, 79 

Folding,  occurrence  and  character  of 12 

Forage,  character  of 15 

Fourth  of  July  Creek,  rocks  on 73 

Fractures,  relation  of,  to  copper 8 

Freighting,  cost  of 17 

G. 

Geography,  description  of 9-10 

Geology,  description  of 11-12,20-26 

Geology,  areal,  description  of 70-71 

Geology,  economic,  account  of 75-108 

Geology,  historical,  sketch  of 71-75 

Gerdine,  T.  G.,  work  of 12 

Glacial  epoch,  events  in 43-48 

Glaciation,  effects  of 18-19 

Glacier  Creek,  rocks  on 61 

Glaciers,  rock,  description  of 52-59 

occurrence  of 15 

origin  of 53-59 

Gold,  discovery  of 76 

placer  deposits  of,  descriptions  of 100-108 

production  of 98 

source  of 98-100 

Gravels,  occurrence  and  character  of 20, 49-51 

Greenstone.  See  Nikolai  greenstone. 
Greenstone-limestone  contact,  copper  along . . 8 

H. 

Historical  geology,  sketch  of 71-75 

Houghton  Alaska  Exploration  Co.,  copper 

prospects  of 97 

Howe,  E..  cited 54-55 

I. 

Idaho  Gulch,  gold  in 100-101 

rocks  near 34 

Igneous  rocks,  distribution  and  character  of.  59-67 

intrusion  of 11,20 

Independence  claim,  description  of 92 

Indians,  homes  of 16 

J. 

Jumbo  claim,  description  of 90-91 

ore  body  of,  section  of,  figure  showing 91 

Jumbo  Creek , fossi Is  from 24 

Jurassic  rocks,  character  and  distribution 

of 11,31-43,63-67 

columnar  sections  of 31,37 

correlation  of 26 

gold  in 8 


K.  Page. 

Kennicott  formation,  age  of 38-43 

character  of 11,19,20,31-42 

columnar  section  of 31,37 

correlation  of 26,31 

deposition  of 72-73 

distribution  of 36-37, 70-71 

fossils  from 38-41 

gold  in 8, 98-99 

views  of 32,64 

Kennicott  Glacier,  breaking  of 14, 47 

description  of 47-48 

fault  at 68-69 

rocks  at  and  near 22, 34, 62, 73 

Kennicott  River,  description  of 10 

Knopf,  A.,  and  Paige,  S.,  cited 67 

Kotsina  River,  copper  on 80 

rocks  on 23,30,62 

Kuskulana  River,  rocks  on 30 

L. 

Lead , occurrence  of 99 

Limestone  contact.  See  Greenstone- lime- 
stone contact. 

Literature,  list  of 13 

Little  Nikolai  Creek,  rock  glacier  on,  view  of. . 56 

Location  of  area 9 

map  showing 9 

Lowlands,  deposits  of. 20 

description  of 20 

M. 

McCarthy  Creek,  correlation  of. 30 

description  of 10, 19, 20, 47 

fan  on,  view  of 18 

fault  on 69 

fossils  from 30,39 

glaciation  on 47-48, 49 

gravels  on 49 

rock  glacier  on 56-59 

view  of 56 

rocks  on 21-22, 23, 28, 29, 31, 33, 62, 70 

valley  of 51 

McCarthy  Creek  glacier,  description  of 47-48 

McCarthy  Creek  shale,  use  of  term 22 

See  also  McCarthy  shale. 

McCarthy  shale,  age  of 30 

character  of 11, 19, 20, 28, 29-30 

correlation  of 27 

deposition  of. 72 

distribution  of 28-29 

fossils  of 30 

Maddren,  A.  G.,  and  Moffit,  F.  H.,  work  of. . 12, 13 

Map  of  Copper  and  Chitina  valleys 9 

of  Nizina  district Pocket. 

Map,  geologic,  of  Nizina  district Pocket. 

Marvellous  claim,  description  of 92-93 

Matanuska  district,  rocks  of. 42, 43, 73-7 4 

rocks  of,  correlation  of 26-27 

Mendenhall,  W.  C.,  work  of. 12 

Mining,  history  of 75-76 

Moffit,  F.  H.,  and  Maddren,  A.  G.,  work  of. . 12,  lo 

N. 

Nabesna- White  River  district,  rocks  of,  corre- 
lation of 20-27 

Naknek  formation,  correlation  of 26 

description  of 26, 42 


INDEX, 


111 


Page. 

National  Creek,  rock  glacier  on 57 

view  of 56 

rocks  on 62 

Native  copper,  occurrence  of 79-80, 105-106 

Nikolai  claim,  description  of 93-95 

map  of. 94 

Nikolai  copper  lode,  discovery  of 75 

exploitation  of 76 

rocks  near,  view  of 32 

Nikolai  Creek,  fault  on 68-69 

fossils  from 24-25, 30, 46 

glaciation  on 48 

rocks  on  and  near 22, 31, 32, 33, 36, 37, 62, 66 

view  of 32 

Nikolai  greenstone,  age  of 63 

character  of 11, 20-21 , 59-62 

copper  in 77-80, 81 

distribution  of 61-62, 70-71 

effusion  of 71-72 

Nizina  district,  copper  of,  survey  of 7 

geologic  map  of Pocket. 

map  of Pocket. 

Nizina  Glacier,  breaking  of 14 

description  of 46-47 

Nizina  River,  description  of 9, 20 

flood  plain  of 50 

glaciation  on 46-47 

rocks  on 21, 22, 23, 28, 31, 37, 61-62, 66, 70 

view  of : 22 

valley  of,  formation  of 75 

Nutzotin  Mountains,  rocks  of 42 

P. 

Paige,  S.,  and  Knopf,  A.,  cited 67 

Physiographic  record,  interpretation  of 74-75 

Placers,  gold,  description  of 100-108 

Pleistocene  epoch , events  in 43-48 

Ponds,  occurrence  of 20 

Population,  character  of 16 

Porphyry  Peak,  rocks  of 37, 66, 71 

view  of 64 

Preglacial  time,  conditions  in 43 

Pyramid  Peak,  rocks  of 34 

Q. 

Quartz  diorite  porphyry,  age  of 66-67 

character  of 63-66 

distribution  of 66,70-71 

intrusions  of,  views  of 64 

Quaternary  deposits,  character  of 11, 20, 49-59 

deposition  of 43-59 

R. 

Rader  Gulch,  gold  in 100-101 

Railroads,  construction  of 17-18 

Relief,  description  of 18-20 

Replacement  deposits,  occurrence  of 77-79 

Rex  Creek,  fossils  from ' 40-41 

glaciation  on 46,47,49 

gold  on 99,103-107 

gravels  of 98 

map  of,  showing  placers 104 

rocks  on 34, 36-38, 66, 68 

Rock  glaciers,  description  of 52-59 

occurrence  of 19 

origin  of 53-59 

Rohn,  Oscar,  work  of 8, 12 

S. 

San  Juan  Mountains,  Colo.,  rock  streams  in...  54-55 
Schrader,  F.  C.,  work  of 71 


Page. 

Schrader,  F.  C.,  and  Spencer,  A.  C.,  cited 62 


work  of 12, 25 

Seattle  Gulch,  gold  in 100-101 

Sedimentary  rocks,  description  of 20-59 

Silver,  occurrence  of 80 

Skolai  Creek,  rocks  on 25 

Skolai  Pass,  rocks  in 25 

Sourdough  Peak,  rock  glaciers  on 58 

rocks  of 37,40,66,71 

Spencer,  A.  C.,  and  Schrader,  F.  C.,  cited. . . 62 

work  of 12,25 

Stanton,  T.  W.,  fossils  determined  by 23-25, 

30, 38-40 

Stratigraphy,  description  of 20-67 

Stream  erosion,  work  of 43 

Stream  gravels,  distribution  and  character  of.  50 

Structure,  description  of 12,67-70 

map  and  sections  showing Pocket. 

T. 

Talkeetna  district,  rocks  of 42, 43 

rocks  of,  correlation  of 26-27 

Talus,  fans  of 19 

Temperature,  records  of 13-15 

Texas  Creek,  glaciation  on 48 

rocks  on 29,40,61 

Till,  distribution  and  character  of 48 

Timber,  character  of 15-16 

Topography,  description  of 18-20 

Trails,  description  of 16-17,20 

Transportation,  cost  of 17 

methods  of 16-18 

Triassic  rocks,  character  and  distribution  of. . 11, 

20-30, 59-63 

correlation  of 27 

view  of 18 

U. 

Unconformity,  occurrence  of 20,29,36 

view  of 36 

V. 

Vegetation,  character  of 15-16 

W. 

Westover  claim,  description  of 95-97 

ore  of 83, 95-97 

White  Creek,  fossils  from 41 

gold  on 103-106 

glaciation  on 46 

map  of,  showing  placers 104 

rock  glacier  on 58 

rocks  on 34,36 

White  River,  copper  on 79-80 

White  River-Nabesna  district,  rocks  of,  cor- 
relation of 26-27 

Williams  Peak,  rocks  of 37 

Witherspoon,  B.  C.,  work  of 7, 12 

Wrangell  Mountains,  description  of 10 

geology  of 10 

Y. 

Young  Creek,  description  of 10 

fault  on 69 

fossils  from 41 

glaciation  on 47, 48, 49, 50 

gold  on 76,98,107-108 

rocks  on  and  near 35-36, 38, 60, 66, 71 

Yukon  Basin,  rocks  of 41,43 

rocks  of,  correlation  of 26-27 


O 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


Bulletin  449 


A GEOLOGIC  RECONNAISSANCE 

IN 

SOUTHEASTERN  SEWARD  PENINSULA  AND 
THE  NORTON  BAY-NULATO  REGION 

ALASKA 


BY 

PHILIP  S.  SMITH  AND  H.  M.  EAKIN 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 


CONTENTS. 


Page. 

Preface,  by  Alfred  H.  Brooks 7 

Introduction  9 

Geography '£ 11 

Location  of  area 11 

History  of  exploration 12 

General  topography 17 

Drainage  basins  included IS 

Yukon  basin 19 

Norton  Sound  drainage 20 

Tributaries  east  of  Koyuk  River 20 

Koyuk  River 24 

Tributaries  west  of  Koyuk  River 25 

Kotzebue  Sound  drainage 28 

Uplands  28 

Coastal  features 30 

Vegetation  and  game 32 

Climate  35 

Temperature v 35 

Precipitation 36 

Wind 37 

Settlements  and  population 38 

Descriptive  geology 39 

Undifferentiated  metamorphic  rocks 39 

Area  east  of  the  Yukon 40 

Southeastern  Seward  Peninsula 40 

Character  and  distribution  of  rocks 40 

Kwik  River  area 41 

Area  north  of  the  Koyuk 42 

Bendeleben  Mountain  area 42 

Area  south  of  the  Niukluk 44 

Area  west  of  the  Darby  range 44 

Summary 45 

Paleozoic  rocks 46 

Area  east  of  the  Darby  range 46 

Fish  River  area 49 

Omilak  mine  area 51 

BJuff— Topkok  Head  area . 52 

Area  at  head  of  the  Mukluktulik 53 

Summary 54 

Cretaceous  sedimentary  rocks 54 

Ungalik  conglomerate 55 

Shaktolik  group 57 

Lower  division 57 

Upper  division 60 


3 


4 


CONTENTS. 


Descriptive  geology — Continued.  Page. 

Igneous  rocks 60 

Pre-Cretaceous 61 

Metamorphic  igneous  rocks— 61 

Nonmetamorphic  igneous  rocks 64 

Post-Cretaceous 70 

Intrusive  rocks 70 

Effusive  rocks  71 

Veins 76 

Unconsolidated  deposits 76 

Unsorted  deposits 76 

Deposits  of  transported  material 77 

Marine  gravels 78 

River  gravels 79 

Glacial  deposits 83 

Age  of  the  unconsolidated  deposits 85 

Structural  geology 86 

Historical  geology 93 

Economic  geology 100 

Placers 101 

Gold  in  areas  of  unmetamorphosed  sediments 101 

Conditions  of  placer  formation 101 

Placers  of  the  Bonanza  Creek  region 105 

Gold  placers  in  areas  of  metamorphic  rocks 109 

Distribution 109 

Koyuk  River  basin 110 

Kwik  River  basin 115 

Tubutulik  River  basin 115 

Kwiniuk  River  basin 116 

Fish  River  basin 116 

Main  stream 116 

Council  region 117 

Bluff  region 123 

Buckland  River  basin 125 

Kiwalik  River  basin 126 

Summary 127 

Lode  prospects 127 

Gold 128 

Silver-lead 130 

Copper  prospects 134 

Coal  resources 136 

Yukon  basin 136 

Norton  Bay  basin  and  southeastern  Seward  Peninsula 139 

Conclusions  regarding  coal  resources 140 


ILLUSTRATIONS. 


Page, 

Plate  I.  Reconnaissance  map  of  southeastern  Seward  Peninsula In  pocket. 

II.  A,  Asymmetric  valley,  Shaktolik  Basin ; B,  uplands  between 

East  Fork  and  Inglutalik 22 

III.  A,  Characteristic  mountain  topography,  Darby  Range;  B,  East 

coast  of  Darby  Peninsula 30 

IV.  Map  showing  distribution  of  timber , 32 

V.  Geologic  map  of  Nulato-Norton  Bay  region In  pocket. 

VI.  Geologic  map  of  southeastern  Seward  Peninsula In  pocket. 

VII.  Geologic  map  of  Omilak  region 44 

VIII.  A,  B,  Paleozoic  limestone,  Darby  Peninsula,  intruded  by  green- 
stone and  by  granite 46 

IX.  A,  Limestone  and  schist  at  Omilak  mine;  B,  General  view  of 

Darby  Range  from  south 50 

X.  A,  Sandstones  and  shales  of  Shaktolik  group  on  Shaktolik 

River ; B,  Concretions  in  sandstones  of  the  Shaktolik  group. _ 56 

XI.  A,  Surface  markings  on  sandstones  of  the  Shaktolik  group, 
Inglutalik  divide;  B , Granite  pinnacles  north  of  Kwiniuk 

River 58 

XII.  A,  Inclusions,  east  coast  Darby  Peninsula ; B,  Venation  in  lime- 
stone, east  coast  of  Darby  Peninsula 66 

XIII.  A , Folded  limestone  near  Omilak  mine;  B,  Folded  and  shat- 
tered limestone  on  Ophir  Creek 90 

Figure  1 . Sketch  map  of  northwestern  Alaska,  showing  location  of  region 

considered 12 

2.  Arrangement  of  drainage  due  to  geologic  structure 23 

3.  Profile  of  hill  north  of  camp  C7,  at  head  of  Tubutulik  River 29 

4.  Relation  of  greenstone,  limestone,  and  slates,  east  coast  of 

Darby  Peninsula 62 

5.  Cliff  exposures  near  mouth  of  Daniels  Creek,  Bluff  region 63 

6.  Sketch  map  of  the  vicinity  of  the  Omilak  mine 64 

7.  Diagram  showing  relations  of  glacial  material  on  Etchepuk 

divide L 85 

8.  Diagrammatic  section  west  of  Traverse  Peak 87 

9.  Diagram  showing  folding  in  two  directions 91 

10.  Diagrammatic  summary  of  geologic  history  of  Nulato-Council 

region 100 

11.  Diagrammatic  cross  section  of  the  Nulato-Norton  Bay  region 

during  Cretaceous  deposition 103 

12.  Sketch  map  of  Alameda  Creek 110 

13.  Sketch  map  and  section  of  Daniels  Creek  placers 123 

14.  Map  showing  location  of  placer  camps  on  Bear  Creek 125 

15.  Diagrammatic  section  of  impregnated  zones,  Bluff  region 129 


PREFACE. 


By  Alfred  TI.  Brooks. 


For  several  years  after  the  organization  of  the  Alaskan  surveys  in 
1898  most  of  the  appropriation  was  devoted  to  exploration.  These 
exploratory  surveys,  although  they  had  no  high  degree  of  accuracy, 
served  to  block  out  the  larger  features  of  the  topography  and  geology, 
and  the  resulting  reports  and  maps  proved  of  great  value  to  the 
pioneer  prospector  and  miner.  With  the  advance  of  the  mining  in- 
dustry came  a constantly  increasing  demand  for  maps  which  were 
based  on  a higher  degree  of  refinement  both  with  reference  to  geo- 
logic observation  and  to  mensuration.  To  meet  this  demand  areal 
surveys  were  begun  first  on  a scale  of  4 miles  to  the  inch  and  later, 
where  the  mining  interests  warranted  it,  on  a scale  of  1 mile  to  the 
inch.  The  rapid  industrial  advancement  in  many  parts  of  Alaska  led 
to  the  expansion  of  surveys  of  this  character  almost  to  the  exclusion 
of  the  purely  exploratory  work. 

The  progress  made  in  reconnaissance  and  detailed  surveys  has 
seemed  to  warrant  again  diverting  a part  of  the  funds  to  exploring 
some  of  the  little  known  regions.  One  of  the  largest  of  the  un- 
surveyed areas  in  the  more  accessible  parts  of  Alaska  is  roughly 
blocked  out  by  lower  Yukon  and  lower  Koyukuk  Rivers  on  the  east 
and  Norton  Bay  and  Seward  Peninsula  on  the  west.  This  field  was 
selected  for  survey  because  it  was  thought  that  the  metamorphic 
rocks  of  the  Seward  Peninsula  might  occur  within  it,  which  would 
give  presumption  of  the  presence  of  auriferous  deposits.  The  results 
of  the  investigation  of  this  area  are  presented  in  this  report. 

In  addition  to  exploring  the  region  east  of  Norton  Bay  the  party 
also  extended  the  topographic  and  geologic  mapping  into  the  south- 
eastern part  of  the  Seward  Peninsula,  thus  extending  the  surveys  of 
Peters  and  Mendenhall,  made  in  1900.  In  this  part  of  the  field  the 
results  were  sufficiently  definite  to  warrant  their  publication  in  a map 
on  a scale  of  4 miles  to  the  inch.  The  remainder  of  the  survey,  based 
as  it  was  on  foot  traverses,  which  afforded  little  opportunity  for  areal 
mapping,  seemed  hardly  sufficiently  accurate  to  warrant  the  publica- 
tion of  maps  on  a larger  scale  than  16  miles  to  the  inch. 


8 


PREFACE. 


Messrs.  Smith  and  Eakin  deserve  great  credit  for  the  large  amount 
of  information  gleaned  during  their  very  hasty  exploration.  The  re- 
sults form  a notable  contribution  to  the  geology  and  geography  of  a 
region  that  was  previously  almost  unknown.  Though  the  economic 
results  so  far  as  most  of  the  region  is  concerned  are  largely  negative, 
they  are,  nevertheless,  of  no  inconsiderable  value.  The  geologic  maps 
will  indicate  large  areas  which  do  not  seem  worthy  of  attention  on  the 
part  of  the  prospector. 

Besides  covering  the  Norton  Bay  and  lower  Yukon  region  in  an 
exploratory  way,  the  report  and  its  maps  furnish  the  details  about  the 
southeastern  part  of  the  Seward  Peninsula  necessary  to  complete  the 
reconnaissance  work  in  that  province.  The  publication  of  this  report 
marks  the  close  of  the  reconnaissance  work  in  the  Seward  Peninsula 
which  was  begun  a decade  ago. 


A GEOLOGIC  RECONNAISSANCE  IN  SOUTHEASTERN 
SEWARD  PENINSULA  AND  THE  NORTON 
RAY-NULATO  REGION,  ALASKA. 


By  Philip  S.  Smith  and  IT.  M.  Eakin. 


INTRODUCTION. 

West  of  Koyukuk  and  Yukon  rivers  a large  area  has  long  remained 
geologically  unexplored.  In  a portion  of  this  region  an  exploration 
party  from  the  United  States  Geological  Survey  worked  during  the 
season  of  1909,  and  the  results  of  the  studies  there  carried  on  and  ex- 
tended as  far  as  Council,  in  Seward  Peninsula,  are  set  forth  in  this 
report.  The  party  consisted  of  the  writers,  A.  G.  Winegarden, 
packer,  and  a cook.  Supplies  for  a month  were  shipped  to  Nulato, 
the  point  from  which  the  expedition  set  out,  and  the  camp  equip- 
ment and  supplies  were  transported  in  the  field  by  a pack  train  of 
four  horses.  Other  supplies,  sufficient  to  last  the  rest  of  the  season, 
were  sent  to  Nome  and  then  transported,  through  the  courtesy  of  the 
Wild  Goose  Company,  to  the  mouth  of  the  Ivoyuk  and  there  cached 
to  await  the  arrival  of  the  party. 

After  many  delays  the  party  arrived  in  Nulato  on  the  afternoon 
of  June  24  and  immediately  began  to  get  the  outfit  into  condition  for 
the  trail.  On  the  morning  of  June  26  active  field  work  was  begun. 
The  route,  as  indicated  by  the  location  of  the  camps  on  the  maps 
(Pis.  I and  Y,  in  pocket),  was  westward  to  Ungalik  River,  thence 
northward  to  the  Ivoyuk,  wThich  was  reached  on  July  16.  Here  a 
halt  was  made  until  supplies  from  the  cache  could  be  obtained  and  the 
outfit  put  into  shape  for  the  next  trip.  On  July  19  the  party  started 
northeastward  along  the  divide  between  the  Inglutalik  and  the 
Koyukuk  drainage  basins.  This  survey  was  carried  eastward  to  the 
divide  between  Ivateel  and  Inglutalik  rivers.  Return  to  the  Ivoyuk 
was  made  along  the  divide  between  the  drainage  basins  of  the  Buck- 
land  and  the  East  Fork  of  the  Ivoyuk,  and  a tie  was  made  on  the 
previous  geological  work  of  Moffit  in  northeastern  Seward  Penin- 
sula. At  the  close  of  the  trip  the  Ivoyuk  was  crossed  near  the  mouth 
of  East  Fork,  and  the  party  arrived  at  the  Ivoyuk  cache  on  August  8. 
A severe  storm  and  the  work  of  replenishing  supplies  and  making 

9 


10 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


necessary  repairs  delayed  setting  out  again  until  August  12,  when 
the  party  got  under  way  and  made  a meandering  traverse  of  the 
areas  between  Koyuk  River  and  Norton  Sound  that  had  not  been 
visited  by  Mendenhall  in  his  expedition  of  1900.  Moving  along  the 
divide  between  the  Koyuk  and  the  Norton  Sound  drainage  basins, 
the  party  swung  around  the  head  of  the  Tubutulik,  thence  crossed 
the  divide  into  the  Fish  River  drainage  basin,  and,  following  along 
the  foothills,  came  to  the  Omilak  mine.  From  the  mine  the  course 
was  southeastward  to  the  Kwiniuk  and  thence  along  the  coast  to 
Walla  Walla.  Supplies  had  been  sent  to  this  point  from  the  mouth 
of  the  Koyuk,  so  that  the  horses  had  been  able  to  travel  light.  From 
Walla  Walla  meandering  traverses  were  made  westward  to  Cheenik, 
which  was  reached  September  IT.  By  this  time  the  top  of  the  ridges 
were  snow  covered,  and  a start  was  made  the  next  day  for  Council  by 
wav  of  the  Kachauik-Fish  River  divide.  Council  was  reached  and 
the  fieldwork  for  the  season  was  stopped  on  September  21. 

Locations  were  kept  by  continuous  foot  traverses  run  b}^  each  of 
the  geologists  independently  and  elevations  were  frequently  noted  by 
aneroid  barometers.  The  barometric  observations,  however,  were  un- 
checked and  served  principally  to  give  relative  elevations.  The  foot 
traverses  were  paced,  directions  being  obtained  by  means  of  Brun- 
ton  compasses.  The  results  of  the  different  traverses  were  platted 
in  the  office  by  making  adjustments  between  known  points  which  had 
been  determined  instrumentally  either  by  the  Coast  and  Geodetic 
Survey  or  by  Peters  on  the  reconnaissance  trip  of  Mendenhall  in  1900. 
So  closely  did  the  various  traverses  check  on  known  points  that  it  P 
believed  that,  after  the  adjustments  were  made  and  the  map  prepared, 
few,  if  anjr,  points  were  more  than  a mile  out  of  their  correct  posi- 
tions. That  this  apparently  rough  method  of  pacing  is  capable  of 
giving  good  results  is  shown  by  the  fact  that  the  difference  between 
the  position  of  Camp  A15,  near  the  Bonanza  mine,  on  the  Ungalik, 
as  determined  by  the  two  geologists,  after  having  made  a linear  trav- 
erse of  over  130  miles,  was  less  than  5 miles.  This  result  was  ob- 
tained on  the  erroneous  premise  that  both  were  pacing  2,000  paces  to 
the  mile.  When,  however,  an  individual  rating  had  been  obtained  by 
comparing  the  scaled  and  paced  distance  to  the  mouth  of  the  Koyuk 
and  this  correction  had  been  applied  to  the  location  of  Camp  A15,  it 
was  found  that  the  difference  between  the  two  traverses  was  consider- 
ably less  than  1 mile. 

Hearty  acknowledgments  are  due  to  Mr.  A.  G.  Winegarden,  of 
Gardiner,  Mont.,  who  acted  as  packer  throughout  the  various  trips, 
for  his  unceasing  activity  in  furthering  the  aims  of  the  expedition 
and  his  willingness  to  perform  more  than  his  share  of  the  camp  work 
in  the  face  of  rather  discouraging  conditions.  Thanks  are  also  ex- 
pressed for  the  friendly  assistance  of  Mr.  C.  H.  Munro,  of  the  Wild 


NORTON  BAY-NULATO  REGION,  ALASKA. 


11 


Goose  Company,  and  to  Messrs.  Thomas  Moon  and  John  Lindburg, 
prospectors,  in  distributing  supplies  at  appointed  places  and  thus 
facilitating  the  movements  of  the  party. 

The  writers  desire  also  to  express  their  appreciation  of  the  work 
of  the  earlier  geologists  and  engineers  who  have  visited  portions  of  the 
region  or  contiguous  areas,  and  from  whose  published  reports  and 
manuscripts  they  have  borrowed  to  supplement  their  own  observa- 
tions. Among  those  to  whom  the  writers  are  most  indebted  for  scien- 
tific information  are  Messrs.  J.  L.  McPherson,  W.  C.  Mendenhall, 
F.  C.  Schrader,  F.  H.  Moffit,  and  A.  H.  Brooks;  for  the  determina- 
tion of  the  fossils  collected  they  are  indebted  to  the  paleontologists 
of  the  United  States  Geological  Survey. 

GEOGRAPHY. 

LOCATION  OF  AREA. 

The  area  in  which  new  geographic  and  geologic  information  has 
been  obtained  may  be  inferred  from  the  description  of  the  itinerary 
of  the  expedition  of  1909.  It  has  seemed  feasible,  however,  to  so 
extend  the  area  actually  visited  as  to  include  contiguous  regions 
which  throw  light  upon  parts  of  the  region  visited  in  1909  or  in 
which  the  results  of  1909  serve  to  confirm  or  explain  problems  raised 
by  other  investigators.  The  area  treated  in  this  report  is  therefore 
in  the  main  rectangular  and  may  be  roughly  described  as  bounded 
by  parellels  64°  and  66°  north  latitude  and  by  meridians  156° 
and.  164°  west  longitude.  Described  in  terms  of  places  and  natural 
objects,  the  southern  margin  is  near  the  settlement  of  Unalaklik,  on 
the  east  coast  of  Norton  Sound,  and  the  eastern  end  of  the  northern 
margin  is  a short  distance  north  of  the  big  bend  of  Koyukuk  and 
Kateel  rivers  and  the  western  end  is  a short  distance  north  of  the 
town  of  Candle  on  Kiwalik  River  in  the  northeastern  corner  of 
Seward  Peninsula.  On  the  east  the  region  is  bounded  by  a north  and 
south  line  passing  a little  east  of  the  junction  of  the  Melozitna  and 
Yukon  rivers;  on  the  west  the  best  known  point  to  which  to  refer  the 
margin  is  the  town  of  Council  on  Niukluk  River.  The  area  can  be 
best  comprehended  by  reference  to  the  general  map  of  northwestern 
Alaska  (fig.  1),  and  to  the  more  detailed  maps,  Plates  I and  V. 
For  several  reasons  it  has  been  decided  to  show  the  eastern  part  of 
this  region  separately  from  the  western.  This  has  been  done  mainly 
because  better  information  has  permitted  mapping  of  the  western 
portion  on  a scale  of  approximately  4 miles  to  the  inch,  whereas  the 
eastern  portion  is  shown  on  Plate  V on  a scale  of  approximately  16 
miles  to  the  inch.  A division  of  this  sort  separates  the  great  sand- 
stone shale  area  of  the  east  from  the  more  highly  metamorphic  areas 
of  the  west.  In  this  report  the  eastern  area,  the  one  represented  by 


12 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


Plate  Y,  will  be  referred  to  as  the  Nulato-Norton  Bay  region,  and  the 
western  part  (Pis.  I,  VI)  will  be  called  southeastern  Seward 
Peninsula. 

HISTORY  OF  EXPLORATION. 

Prospectors  and  trappers  have  without  doubt  wandered  over  the 
region  described  in  this  report,  but  there  is  little  or  no  record  of  their 
journeys  and  the  facts  that  they  learned  have  been  lost.  Other 
classes  of  travelers  seldom  ventured  far  from  the  main  avenues  of 
intercommunication;  consequently,  until  within  the  last  10  or  15 
years  there  have  been  few  published  references  to  any  part  of  the 


Figure  1. — Sketch  map  of  northwestern  Alaska,  showing  location  of  region  considered. 

region  except  the  coast  line,  the  Yukon  and  Ivoyukuk  rivers,  and  the 
Kaltag  portage.  It  is  not  intended  at  this  place  to  give  an  account 
of  all  the  exploring  expeditions  that  have  visited  the  waters  sur- 
rounding Seward  Peninsula,  Norton  Sound,  and  Bering  Sea,  and  the 
reader  who  desires  a more  complete  historical  sketch  is  referred  to 
the  papers  of  Brooks0  and  Dall.ft 

The  oldest  settlement  in  this  part  of  Alaska  was  at  St.  Michael, 
where,  according  to  Dali,0  Michael  Tebenkoff,  an  officer  in  the  Rus- 

“ Brooks,  A.  H.,  Geography  and  geology  of  Alaska  : Prof.  Paper  U.  S.  Geol.  Survey 
No.  45,  1906. 

6 Dali,  W.  H.,  Alaska  and  its  resources,  Boston,  1870,  627  pp.  and  map. 
c Idem,  p.  9. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


13 


sian- American  Trading  Company,  established  a post  in  1833.  From 
this  point  trading  was  carried  on  with  the  surrounding  country. 
Soon  other  posts  were  established.  Thus  in  1838,®  Malakoff,  a creole, 
explored  the  Yukon  as  far  north  as  the  present  town  of  Nulato  and 
established  a small  settlement  at  the  mouth  of  Nulato  River.  He  left 
this  post  undefended  during  the  winter  of  1838-39  and  it  was  de- 
stroyed by  Indians.  Soon  afterward,  in  1840,  a trading  post  and  fort 
were  established  on  Norton  Bay  near  the  mouth  of  Unalaklik  River 
and  called  by  the  name  of  the  stream.  This  town,  according  to  the 
1900  census,  had  a population  of  241. 

In  spite  of  the  destruction  of  the  first  settlement  at  the  mouth  of 
Nulato  River  the  Russian- American  Trading  Company,  appreciating 
the  importance  of  this  place  as  a point  giving  ready  access  to  the 
Koyukuk  basin,  sent  Derabin  in  1841  to  rebuild  the  fort.  This  was 
done,  and  in  1842  Lieutenant  Zagoskin  of  the  Russian  navy  visited 
the  place.  His  visit  is  of  interest  because  he  made  several  short 
journeys  into  adjacent  areas  and  published  the  results  of  his  observa- 
tions.* &  Although  his  accounts  are  fragmentary  and  imperfect,  they 
show  that  he  visited  portions  of  Yukon  River  as  far  upstream  as  the 
mouth  of  the  Melozitna,  explored  Koyukuk  River  as  far  as  the  mouth 
of  the  Kateel,  and  made  a side  trip  up  the  Ivateel  to  assure  himself 
that  the  native  reports  of  an  easy  route  into  the  Buckland  drainage 
basin  were  correct.  Unfortunately  the  maps  published  with  his  re- 
port are  not  based  so  much  upon  his  direct  personal  observations  as 
upon  reports  heard  by  him,  and  consequently  many  of  the  features 
are  indicated  only  in  a most  general  manner. 

In  1851  the  trading  post  and  fort  at  Nulato  were  burned  and  some 
of  the  inhabitants  were  massacred  by  Indians  from  the  Koyukuk. 
When  the  town  was  rebuilt  it  was  moved  a mile  or  more  up  the  river 
to  its  present  location  on  a low  gravel  bench  between  Nulato  Slough 
and  Nulato  River. 

About  1850  the  great  activity  among  many  of  the  different  nations, 
notably  the  English,  in  searching  for  the  Franklin  expedition  re- 
sulted in  several  ships  wintering  in  the  waters  of  Kotzebue  Sound. 
From  these  ships  several  exploring  parties  visited  neighboring  areas 
and  added  geographical  data.  Of  these  expeditions  few  prepared 
maps  of  sufficiently  large  scale  to  portray  any  but  the  most  general 
features  of  the  region  explored.  Among  the  overland  trips  were 
the  exploration  of  Selawik  Lake  and  vicinity  by  Surgeon  Simpson 
of  H.  M.  S.  Plover , the  trip  from  Chamisso  Island  by  way  of  Buck- 
land  and  Koyuk  rivers  to  St.  Michael  by  Lieutenant  Pirn  of  the  same 

a Dali,  W.  H.,  Alaska  and  its  resources,  1870,  p.  48. 

6 Zagoskin,  L.  A.,  Travels  on  foot  and  description  of  the  Russian  possessions  in  America 
from  1842  to  1844  : Ermans  Archiv  fur  wissenschaftl.  Kunde  von  Russland,  vols.  6 and  7. 


14 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


ship,  and  the  exploration  of  Buckland  River  by  Captain  Kellett  and 
officers  of  H.  M.  S.  Herald.  Accounts  of  the  voyages  of  the  Herald  ° 
show  that  the  last-named  expedition  went  up  the  Buckland  for  30 
miles  (probably  measured  along  the  circuitous  course  of  the  river) 
in  a whaleboat  and  then  about  30  miles  farther  in  lighter  boats.  The 
Pirn  journey  is  also  described  in  the  same  publication,  but  the  narra- 
tive is  more  a recital  of  hardships  than  of  geographic  or  geologic 
data  and  is  not  accompanied  by  a map.6 

A later  impetus  to  exploration  was  given  when  in  1863  the  Western 
Union  Telegraph  Company  undertook  to  build  a telegraph  line 
through  Alaska  to  connect  the  settled  parts  of  America  and  Europe. 
In  1865  Kennicott,  who  was  in  charge  of  the  scientific  work  of  this 
company,  crossed  the  Kaltag  portage  and  surveyed  the  route  to 
Nulato.  During  the  same  year  J.  T.  Dyer  and  R.  D.  Potter,  accord- 
ing to  Dall,c  made  a very  hazardous  and  successful  exploration  of 
the  country  between  Norton  Bay  and  the  mouth  of  the  Koyukuk 
River  on  the  Yukon.  Unfortunately  no  map  of  this  trip  was  pub- 
lished, and  the  data  collected,  although  undoubtedly  used  by  Dall,d 
have  never  been  available.  In  1865,  also,  another  party  under  the 
leadership  of  Baron  von  Bendeleben  explored  the  route  for  the  line 
from  Norton  Bay  to  Port  Clarence,  but  the  results  like  those  of  the 
other  parties  have  never  been  published. 

The  death  of  Kennicott  in  1866  caused  the  leadership  of  the  sci- 
entific corps  to  pass  to  W.  H.  Dali.  It  was  the  work  accomplished 
while  in  charge  of  the  telegraph  exploration  and  during  the  year 
succeeding  the  abandonment  of  the  enterprise  that  enabled  Mr.  Dali 
to  write  the  most  authoritative  general  book  on  Alaska  that  had 
appeared  up  to  the  time  of  the  discovery  of  valuable  gold  deposits. 
All  branches  of  geography  and  geology  received  some  attention  from 
this  investigator  and  many  of  his  observations  will  be  quoted  in  more 
detail  in  subsequent  portions  of  this  report. 

A period  of  ten  or  fifteen  years  elapsed  during  which  few  notes 
of  value  were  collected  and  published  concerning  the  Nulato-Council 
region.  In  1885  Lieutenant  Allen  made  his  famous  trip,  during 
which  a portion  of  the  Koyukuk  was  mapped  and  also  the  portage 
from  Kaltag  to  Unalaklik.  About  this  time  explorations  by  the 
Revenue-Cutter  Service  were  begun.  The  explorations  of  this 
branch  of  the  government  service  which  directly  concerned  the 
Nulato-Council  region  were  by  Purcell  in  the  vicinity  of  Selawik 
Lake  and  by  Zane  along  the  Koyukuk  to  Nulato. 

° Seeman,  Berthold,  Navigation  of  H.  M.  S.  Herald  during  the  years  1845-1851,  vol.  2, 
London,  1853,  pp.  119-120. 

b Op.  cit.,  pp.  130-148. 

c Dali,  W.  H.,  Alaska  and  its  resources,  p.  357. 

d Op.  cit.,  map. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


15 


In  1889  Prof.  I.  C.  Russell  ° ascended  the  Yukon,  and  his  report 
of  this  trip  furnished  many  facts,  both  of  geologic  and  geographic 
significance. 

With  the  discovery  of  gold  in  the  Klondike  an  influx  of  pros- 
pectors and  others  into  Alaska  followed,  and  soon  afterwards  the 
United  States  Geological  Survey  was  able  actively  to  undertake  geo- 
graphic and  geologic  investigations  of  the  district.  One  of  the 
earliest  of  these  surveys  was  conducted  by  Spurr,&  mainly  in  the 
basin  of  the  Kuskokwim.  The  geologic  and  topographic  map  pub- 
lished with  his  report  covers  the  area  between  the  Ivoyukuk  and  the 
Koyuk  and  from  the  mouth  of  the  Kateel  southward,  and  is  con- 
sequently the  first  geologic  map  of  the  eastern  half  of  the  area  studied 
in  1909.  Most  of  the  information  concerning  the  Nulato-Council 
region  was  compiled  or  gathered  from  reports  of  prospectors,  and 
very  little  geographic  significance,  outside  of  the  distribution  of  the 
different  geologic  groups,  was  added. 

Schrader  c in  1899  came  clown  the  Ivoyukuk  and  the  maps  published 
in  the  report  of  his  trip,  which  were  made  by  T.  G.  Gerdine,  afford 
a much  more  detailed  representation  of  the  region  than  had  hitherto 
been  available.  No  traverses  of  the  country  away  from  the  river 
were  made,  so  that  details  regarding  the  region  between  the  Yukon 
and  Norton  Bay  were  not  acquired.  At  the  close  of  the  field  work  in 
the  Ivoyukuk  region  Schrader  went  to  Nome  and  with  Brooks  made 
the  first  examination  by  Survey  geologists  of  Seward  Peninsula. 

In  1900  two  main  parties  were  dispatched  to  Seward  Peninsula. 
One  in  charge  of  A.  H.  Brooks  investigated  the  region  as  far  east 
as  Council ; the  other  in  charge  of  W.  J.  Peters,  with  W.  C.  Menden- 
hall as  geologist,  investigated  the  southern  part  of  the  peninsula 
as  far  east  as  the  Koyuk.  The  field  studies  of  the  Peters  party 
cover  the  western  part  of  the  area  visited  by  the  expedition  of  1909 
and  will  be  referred  to  in  detail  in  succeeding  pages  of  this  report. 
In  the  main,  however,  the  results  may  be  summarized  as  follows: 
A delineation  of  the  major  features  of  the  topography  by  maps,  the 
publication  of  data  on  various  geographic  subjects  such  as  climate, 
vegetation,  and  fauna,  and  the  statement  both  verbal  and  graphic 
of  the  areal,  historical,  and  economic  geology.**  The  studies  of  Men- 
denhall were  carried  on  mainly  from  the  streams;  the  three  larger 
ones,  the  Fish,  the  Tubutulik,  and  the  Koyuk,  he  ascended  in  canoes. 

° Russell,  I.  C.,  Notes  on  the  surface  geology  of  Alaska : Bull.  Geol.  Soc.  America, 
vol.  I,  pp.  99-162. 

b Spurr,  J.  E.,  A reconnaissance  in  southwestern  Alaska  in  1898 : Twentieth  Ann. 
Rept.  U.  S.  Geol.  Survey,  pt.  7,  1909,  pp.  31-264. 

c Schrader,  F.  C.,  Preliminary  report  on  a reconnaissance  along  Chandlar  and  Koyukuk 
rivers.  Alaska,  in  1899 : Twenty-first  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  2,  1900,  pp. 
441-486. 

d Mendenhall,  W.  C.,  A reconnaissance  in  the  Norton  Bay  Region,  Alaska,  in  1900,  a 
special  publication  of  the  U.  S.  Geol.  Survey,  1901,  pp.  183-222. 


16 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


During  1901  Schrader  made  a trip  to  northern  Alaska  and  yisited 
portions  of  the  Koyukuk  drainage  basin.®  In  the  same  year  Menden- 
hall b explored  the  Kobuk  River,  and  although  this  region  lies  con- 
siderably to  the  north  of  the  Nulato-Council  area  the  information 
secured  throws  considerable  light  on  the  problems  of  the  latter.  In 
the  reconnaissance  by  Schrader,  a geologic  map  was  published  show- 
ing the  different  formations  along  the  Koyukuk  northwestward  from 
latitude  66°  north,  and  this  map  and  the  notes  on  the  lower  part  of 
the  river  already  referred  to  on  page  15  afford  a continuous  sec- 
tion from  the  Yukon  northward. 

Of  the  other  survey  expeditions  that  have  visited  contiguous  areas 
the  party  under  Collier  in  1902  and  the  Atwood  party  of  1907  are 
the  only  ones  that  require  specific  reference  here.  The  main  object 
of  these  expeditions  was  to  study  the  coal  resources  of  portions  of 
Alaska.  A publication  has  appeared  setting  forth  the  results  of  the 
investigations  by  Collier,®  but  Atwood’s  report  has  not  yet  been 
published,  though  many  of  the  manuscript  notes  have  been  kindly 
furnished  to  the  present  writers.** 

In  1906  a traverse  from  the  mouth  of  the  Koyukuk  to  the  shores  of 
Norton  Sound  and  thence  to  Council  was  made  by  a party  sent  out 
by  the  War  Department.  The  object  of  the  survey  was  to  determine 
the  feasibility  of  a land  route  from  the  navigable  waters  of  the 
Tanana  to  the  vicinity  of  Council  City.  The  maps  accompanying  the 
report  of  this  survey  were  the  first  to  give  accurate  information  con- 
cerning a strip  of  country  5 to  10  miles  wide  extending  from  the 
mouth  of  Koyukuk  to  the  mouth  of  the  Ivoyuk,  and  are  replete  with 
facts  of  geographic  interest.  J.  L.  McPherson  was  in  charge  of  the 
field  work  and  prepared  the  text  of  the  report.®  Specimens  of  the 
various  formations  crossed  were  collected  and  submitted  to  the  United 
States  Geological  Survey  for  study.  On  this  account  it  was  not  neces- 
sary to  cover  the  area  surveyed  by  McPherson’s  party  again  when  the 
Nulato-Council  region  was  visited  in  1909.  Reference  to  this  report 
will  be  made  in  more  detail  in  subsequent  pages  of  this  paper. 

In  1908  A.  G.  Maddren  made  an  exploratory  survey  of  Innoko 
River  and  contiguous  areas.  His  report  on  this  trip,  with  the  accom- 
panying maps,  affords  considerable  information  concerning  the 

« Schrader,  F.  C.,  Reconnaissance  in  northern  Alaska  in  1901  : Prof.  Paper  U.  S.  Geol. 
Survey  No.  20,  1904,  139  pp. 

b Mendenhall,  W.  C.,  Reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska : 
Prof.  Paper  U.  S.  Geol.  Survey  No.  10,  1901,  68  pp. 

« Collier,  A.  J.,  Coal  resources  of  the  Yukon,  Alaska  : Bull.  U.  S.  Geol.  Survey  No.  218, 
1903,  71  pp. 

d Atwood,  W.  W.,  Geology  and  mineral  resources  of  parts  of  the  Alaska  Peninsula  : Bull. 
U.  S.  Geol.  Survey  No.  467,  in  preparation. 

c McPherson,  .T.  L.,  Reconnaissance  and  survey  for  a land  route  from  Fairbanks  to 
Council  City,  Alaska  : Sen.  Doc.  No.  214,  59th  Cong.,  2d  sess.,  1907,  22  pp.,  7 maps,  6 
plates. 


NORTON  BAY-NULATO  REGION,  ALASKA.  17 

country  south  of  the  Yukon.  Practically  all  the  features  shown  on 
Plate  V south  of  the  Yukon  were  taken  directly  from  his  maps." 

GENERAL  TOPOGRAPHY. 

Throughout  the  Nulato- Council  region  the  relief  is  relatively  low. 
Few  hills  over  3,000  feet  occur  and  the  larger  part  of  the  upland  area 
is  only  about  2,000  feet  above  sea  level.  Although  there  are  no  high 
ranges,  steep  slopes  lead  from  the  flat  river  bottoms  to  the  high- 
lands. In  the  Nulato-Norton  Bay  region  there  are  numerous  parallel 
northeast-southwest  ridges,  the  highest  of  which  forms  the  divide 
between  the  Inglutalik-Ungalik  and  the  Kateel-Gisasa  river  basins. 
The  hills  to  the  north  of  the  East  Fork  of  Koyuk  River  are  low  and 
rolling,  without  pronounced  direction.  Farther  west,  in  Seward  Pen- 
insula, there  are  three  ranges  forming  prominent  landmarks;  these 
are  the  hills  between  Buckland  and  Kiwalik  Rivers,  and  the  Darby 
and  the  Bendeleben  Mountains.  The  higher  points  of  the  first  range 
rise  to  elevations  of  about  2,500  feet;  in  the  Bendeleben  Mountains 
the  highest  point  is  a little  over  3,700  feet,  and  in  the  Darby  Range 
the  highest  peak  is  about  3,000  feet.  In  the  two  last-named  ranges 
precipitous  slopes  more  than  2,000  feet  high  give  a very  rugged 
topography. 

Outside  of  these  three  higher  areas  the  uplands  are  rolling,  with 
elevations  from  1,000  to  2,000  feet  above  sea  level,  unforested,  well 
drained,  and  covered  with  angular  fragments  of  frost-riven  waste. 
Pinnacles  of  the  underlying  rocks  form  fantastic  knobs  here  and 
there. 

The  drainage  of  the  region  studied  flows  into  the  Yukon,  into  Nor- 
ton Bay,  into  Norton  Sound,  or  into  Kotzebue  Sound.  The  streams 
belonging  to  the  Yukon  drainage  and  to  the  eastern  part  of  Norton 
Bay  show  pronounced  parallelism  with  the  geological  structure,  and 
long,  narrow  valleys  are  the  result.  The  gradients  of  the  main  valleys 
are  low,  but  those  of  the  small  side  streams  rise  rapidly  headward. 
In  places  the  streams  flow  through  narrow  rock-walled  canyons  of 
slight  depth,  but  in  others  flat  flood  plains  and  gravel  deposits  occur. 
In  the  headward  portions  of  the  basins  complex  relations  of  the 
streams  on  opposite  sides  of  the  divide  are  noted,  and  it  is  by  no 
means  possible  at  long  range  to  foretell  the  direction  of  the  drainage. 
In  Seward  Peninsula,  where  the  geologic  structure  is  more  complex, 
the  effect  on  the  streams  is  not  well  marked  and  irregular  courses  are 
the  rule.  In  this  part  of  the  area  the  longer  streams,  such  as  the 
Koyuk,  the  Kiwalik,  and  the  Tubutulik,  flow  more  or  less  parallel 

" Maddren,  A.  G.,  The  Innoko  gold-placer  district,  Alaska : Bull.  U.  S.  Geol.  Survey 
No.  410,  1910,  pis.  I and  II. 

71469°* — Bull.  449—11 2 


18 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


with  the  mountains,  but  Fish  River  and  its  larger  tributaries  flow  at 
right  angles  to  the  Bendeleben  Range. 

Almost  all  the  valleys  show  signs  of  having  been  eroded  entirely 
by  stream  action.  In  the  headwaters  of  the  rivers  rising  in  the 
Bendeleben  and  the  Darby  Ranges,  however,  there  are  glacial  cirques 
and  valleys.  Here  the  present  streams  form  irregular  threads  on  the 
broadly  open  floors  of  valleys  with  very  steep  sides.  At  the  mouths 
of  the  streams  flowing  into  Norton  Bay  many  of  the  streams,  instead 
of  showing  erosion  features,  have  filled  the  former  valleys,  which 
have  been  depressed,  with  sand  and  gravel.  Examples  of  this  kind 
of  topography  are  found  at  the  mouth  of  the  Kwik,  the  Tubutulik, 
and  the  Kwiniuk  Rivers,  where  numerous  lakes  and  sloughs  form  an 
untraversable  network  during  the  summer. 

The  coast  line  presents  numerous  examples  of  different  types  of 
shore  topography.  From  the  Reindeer  Hills  to  the  Koyuk  a coastal 
plain,  recently  emerged,  affords  a relatively  straight  shore  with  such 
slight  depths  of  water  off  the  coast  that  approach  for  large  vessels 
is  impossible.  Of  course,  under  such  conditions,  harbors  do  not  exist. 
On  the  western  side  of  Norton  Bay  the  sinking  of  the  land  and  the 
attack  of  the  waves  have  resulted  in  a rugged  coast  with  cliffs  and 
harbors.  This  part  of  the  coast  is  formed  by  the  Darby  Range, 
which  rises  in  abrupt  slopes  from  the  sea  and  forms  a long  southward 
pointing  peninsula.  West  of  this  range  the  deep  reentrant  of  Go- 
lofnin  Sound  and  Bay,  which  probably  represents  the  submerged 
portion  of  an  old  valley  similar  to  that  of  Fish  River,  affords  a good 
harbor.  Still  farther  west  rocky  headlands  wTith  intervening  beaches 
produce  a diversity  of  forms.  On  the  depressed  portions  of  the  coast 
there  are  sand  spits,  such  as  the  long  point  extending  east  from  near 
the  mouth  of  the  Kwiniuk. 

DRAINAGE  BASINS  INCLUDED. 

All  the  streams  flowing  through  the  Nulato-Council  region  may 
be  considered  as  belonging  to  one  of  three  main  basins,  namely,  the 
Yukon,  the  Norton  Sound,  and  the  Kotzebue  Sound.  Of  these  the 
first  two  include  by  far  the  greater  number  of  streams.  Roughly 
computed  about  50  per  cent  of  the  area  shown  on  the  maps,  Plates  I 
and  V,  is  drained  by  the  Yukon  and  its  tributaries,  45  per  cent  by 
tributaries  to  Norton  Sound,  and  5 per  cent  by  streams  flowing  into 
Kotzebue  Sound.  In  the  description  of  these  different  basins  no 
attempt  will  be  made  to  enumerate  all  the  streams  belonging  to  each, 
for  that  sort  of  information  may  be  better  gathered  from  the  maps 
(Pis.  I and  Y),  but  rather  to  present  the  particular  features  not  easily 
legible  on  topographic  maps  of  such  scales  as  those  adopted  for 
publication.  • 


NORTON  BAY-NULATO  REGION,  ALASKA. 


19 


YUKON  BASIN. 

The  portion  of  the  Yukon  considered  in  this  report  extends  from 
slightly  east  of  the  mouth  of  the  Melozitna  on  the  northeast  to  near 
the  mouth  of  Ivaiyuh  Slough  on  the  southwest.  In  this  distance  the 
main  tributaries  are  the  Koyukuk,  the  Nulato,  the  Kaltag,  and  the 
Khotol.  Regarding  these  various  streams,  with  the  exception  of 
the  first  two,  no  new  data  of  geographic  interest  were  received  during 
1909,  and  as  the  facts  already  known  about  the  Kaltag  and  the 
Khotol  are  indicated  on  the  map  accompanying  these  reports-,  no 
further  description  of  them  will  be  attempted. 

Kateel  and  Gisasa  rivers  formed  the  portions  of  the  Koyukuk  drain- 
age that  were  visited  and  mapped,  but  only  the  upper  30  to  50  miles 
of  each  stream  were  seen  in  any  detail.  McPherson,  who  crossed 
the  Gisasa  near  latitude  65°  North,  describes  the  valley  as  follows:0 

The  Gisasa  River  is  a stream  from  70  to  150  feet  wide,  with  gravelly  bottom. 
Along  the  river  banks  on  the  north  side  of  the  valley  is  a heavy  growth  of 
spruce.  Along  the  south  side  of  the  valley  timber  grows  in  scattered  bunches, 
the  intervening  ground  being  to  a considerable  extent  marshy  and  niggerhead 
tundra. 

From  the  survey  of  1909  it  was  found  that  the  Gisasa  Basin  was  a 
peculiar,  narrow  one,  lying  between  the  Nulato  on  the  southeast  and 
the  Kateel  on  the  northwest.  The  river  from  mouth  to  head  near 
Camp  A9  must  be  nearly  TO  miles  in  a direct  line.  In  this  distance 
few  or  no  tributaries  much  more  than  10  miles  in  length  are  received. 
The  basin  is  thus  probably  less  than  a score  of  miles  wide  in  its 
widest  part,  and  in  the  headward  50  miles  it  is  generally  much  less. 

As  will  be  shown  in . a later  portion  of  this  report  the  direction 
and  the  general  physical  features  of  the  Gisasa  Valley  are  due  to  the 
geologic  structure  of  the  region,  which  trends  northeast-southwest. 
Although  in  portions  of  its  course!  the  river  flows  on  a flat  gravel 
plain  essentially  at  the  level  of  the  stream,  in  other  parts  it  has  rock 
walls  through  which  the  stream  has  cut  narrow  canyons.  These 
canyons  are  not  continuous,  but  appear  at  irregular  intervals  along 
the  valley.  None  of  the  canyons  are  deep,  only  a.  few  of  the  rock 
walls,  if  any  of  them,  reaching  a height  of  50  feet.  Above  the  steeply 
incised  walls  a more  open  valley  is  usually  found,  which  indicates 
rather  recent  minor  deformation  of  an  anterior  topography. 

The  Kateel  Basin  was  seen  in  less  detail  by  the  writers,  but  its 
general  features  are  essentially  similar  to  those  of  the  Gisasa,  except 
that  its  valley  is  wider  and  it  has  longer  tributaries.  From  the 
survey  of  McPherson  it  was  determined  that  Arvesta  and  Caribou 
creeks  are  tributaries  of  the  Kateel.  The  former,  where  it  was 
crossed,  near  latitude  65°  north,  is  from  50  to  70  feet  wide  and  from 
1 to  3 feet  deep.  The  latter  is  much  smaller  and  runs  at  an  elevation 


° McPherson,  J.  L.,  op.  cit.,  p.  17. 


20 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


about  500  feet  higher.  Prospectors  who  crossed  the  region  somewhat 
north  of  McPherson’s  route  state  that  the  volume  of  the  Kateel  is 
much  smaller  than  that  of  the  Gisasa, 

A general  idea  of  the  Kateel  Basin  was  afforded  by  a view  from 
Traverse  Peak,  though  the  weather  was  unfavorable  for  a thoroughly 
satisfactory  observation  of  the  topography.  From  this  point  it  was 
evident  that  the  northeasterly  trend  observed  in  the  Gisasa  Valley 
was  still  dominant.  The  divide  along  the  western  margin  of  the 
basin  ran  nearly  north  and  south,  so  there  is  a considerable  area 
tributary  to  this  river.  Low  passes  lead  from  the  Kateel  into  the 
Ungalik,  or  into  the  Inglutalik,  and  probably  into  the  Buckland.  The 
pass  from  the  Kateel  to  the  Buckland  was  not  actually  seen,  but 
enough  of  the  drainage  arrangement  was  evident  to  show  that  some 
of  the  western  tributaries  joining  the  Kateel  below  its  junction  with 
Arvesta  Creek  head  in  the  low  hills  east  of  the  Buckland,  so  that  an 
easy  route  undoubtedly  exists  between  the  two  rivers. 

The  Nulato  River  Basin  is  long  and  narrow,  being  formed  by  two 
large  streams  occupying  strike  valleys  that  coalesce  a few  miles  from 
the  Yukon  and  below  this  point  are  transverse  to  the  structure.  The 
main  branch  is  about  50  miles  long  in  a straight  line.  Its  valley  has 
a broad  gravel-filled  floor  on  which  the  stream  meanders  in  irregular 
pattern.  It  Avill  be  seen  from  the  map  of  this  valley  that,  although 
lying  parallel  with  the  Yukon  and  not  more  than  20  or  at  most  25 
miles  away  from  that  stream,  it  drains  northeastward,  whereas  the 
Yukon  in  that  part  of  its  course  flows  southwestward.  This  results 
in  a more  than  right-angled  turn  near  the  mouth  of  the  Nulato,  and 
suggests  that  the  physiographic  development  of  the  streams  has  been 
complex.  Smooth  slopes  rise  steeply  from  the  valley  floor  to  the 
relatively  even  uplands.  On  the  southeastern  side  high  hills  scored 
by  narrow  gulches  preserve  the  snowfall  late  in  the  summer.  The 
volume  of  water  carried  by  the  main  branch  is  therefore  more  con- 
stant throughout  the  season  than  is  the  case  of  those  streams  depend- 
ent upon  the  rainfall.  Passes  easily  traversable  by  horses  lead  from 
the  Nulato  Basin  to  that  of  the  Gisasa,  of  the  Shaktolik,  and  prob- 
ably also  of  the  Unalaklik. 

NORTON  SOUND  DRAINAGE. 

TRIBUTARIES  OF  NORTON  SOUND  EAST  OF  KOYUK  RIVER. 

East  of  Koyuk  River  the  main  streams  belonging  to  the  Norton 
Sound  drainage  from  south  to  north  are  the  Unalaklik,  the  Shaktolik, 
the  Ungalik,  and  the  Inglutalik.  All  of  these  rivers  show  pro-^ 
nounced  angular  bends  on  a large  scale,  most  of  which  are  to  be 
accounted  for  by  the  geologic  structure  of  the  region.  This  condi- 
tion is  best  illustrated  by  the  three  northern  streams,  whose  basins 
are  almost  completely  mapped.  It  will  be  seen  from  the  map  that 


NORTON  BAY-NULATO  REGION,  ALASKA.  21 

for  the  first  5 or  10  miles  8 in  a straight  line  from  the  coast  the  rivers 
flow  in  winding  courses  at  a right  angle  to  the  shore.  Upstream 
from  this  point  the  course  abruptly  changes,  and  for  the  next  10  to 
30  miles  the  rivers  have  a nearly  north-south  trend.  Still  farther  up- 
stream the  direction  again  changes,  and  the  streams  flow  from  the 
northeast  or  even  from  the  east-northeast. 

Taken  as  a whole,  the  three  rivers  have  narrow,  rather  contracted 
basins  in  the  middle  or  north-south  part  of  their  courses,  because  few 
tributaries  enter  from  the  east  and  west ; in  the  upper  part,  however, 
because  the  main  streams  are  flowing  more  or  less  across  the  geologic 
structure,  the  side  streams  are  long  and  the  area  tributary  to  the 
main  streams  is  therefore  more  extensive.  Rock- walled  canyons, 
separated  from  each  other  by  gravel-filled  basins,  bear  witness  to 
recent  crustal  movements  throughout  the  area. 

Unalaklik  River  was  not  visited  by  the  survey  party  in  1909,  but 
portions  of  it  are  well  known,  because  the  portage  from  the  Yukon  to 
St.  Michael  follows  the  lower  part  of  this  stream.  A long  branch 
joining  from  the  north  heads  against  the  Shaktolik  River,  and  it  is 
probable  that  an  easy  pass  across  the  hills  to  Nulato  River  exists.  The 
northeast-southwest  trend  of  the  drainage  and  the  intricacy  of  stream 
arrangements  make  it  difficult  to  interpret  the  topography  at  long 
range.  It  is  possible,  therefore,  that  the  Shaktolik  may  extend  far- 
ther around  the  head  of  Nulato  River  than  was  evident  at  a distance, 
so  that  there  may  be  more  than  one  divide  between  Nulato  and 
Unalaklik  rivers. 

North  of  the  Unalaklik  is  a rather  small  stream,  the  Iguik,  which 
drains  the  triangular  area  between  the  Unalaklik  and  the  Shaktolik. 
Its  drainage  basin  is  at  most  only  a few  hundred  square  miles  in  area. 

Although  previously  mapped  as  a rather  unimportant  river,  the 
Shaktolik  drains  a considerable  territory  between  the  Ungalik  on  the 
north  and  the  Unalaklik  on  the  south.  Its  course  is  so  irregular  that 
it  can  with  difficulty  be  recognized  at  any  considerable  distance.  The 
Shaktolik  was  first  seen  in  detail  near  camp  A10.  At  this  place  its 
course  was  nearly  due  north,  giving  the  impression  that  it  flowed 
northward  into  the  Ungalik.  Near  camp  A13,  however,  it  joined 
with  a branch  from  the  south  and  formed  a good-sized  stream.  From 
the  small  increase  in  the  size  of  the  northern  branch  between  camp 
A10  and  its  junction  east  of  camp  A13  it  seems  certain  that  only  a 
few  tributaries  enter  between  these  two  places. 

Near  camp  A10  the  river  is  incised  in  a narrow  rock-walled  canyon 
about  30  feet  deep.  Above  the  canyon  walls  the  topography  opens 
out  into  a broad  older  valley  which  had  reached  maturity  before  the 
uplift  took  place  by  which  the  present  cycle  was  started.  The  floor 

° The  figures  given  represent  measurements  in  an  air-line  and  not  along  the  circuitous 
courses  of  the  streams. 


22 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


of  this  older  valley  is  in  large  measure  rock  cut  with  a relatively 
small  amount  of  gravel  covering.  Well-rounded  material,  however, 
is  practically  universally  present  and  affords  indisputable  proof  of 
the  presence  of  stream  erosin  at  this  higher  level.  Near  camp  A13 
the  canyon-like  character  is  wanting.  Four  or  5 miles  below  camp 
A14  incised  meanders,  with  radii  of  from  one-half  mile  to  1 mile, 
occur.  Here  the  walls  are,  for  the  most  part,  gravel,  with  the  bed- 
rock not  exposed.  It  is  believed  that  the  differences  in  the  amount 
of  filling  and  incision  noted  along  this  stream  are  due  to  the  undula- 
tory  character  of  the  most  recent  uplift. 

No  accurate  determinations  were  made  of  the  volume  of  the  Shak- 
tolik,  but  from  float  measurements  near  camp  A12  it  was  found  that 
the.  discharge  was  between  150  and  200  second-feet.  The  tributary 
from  the  north  joining  east  of  camp  A13  was  of  about  equal  vol- 
ume, and  below  camp  All  the  amount  of  water  had  increased  to 
such  an  extent  that  the  stream  could  be  crossed  only  with  difficulty. 
In  this  connection  it  should  be  noted  that  1909  was  an  exceptionally 
dry  season,  so  that  a greater  volume  is  to  be  expected  during  a year 
of  normal  precipitation. 

Ungalik  River  shows  the  same  characters  as  the  other  streams 
tributary  to  Norton  Bay  from  the  east.  Its  basin  shows  the  three 
distinct  parts  previously  referred  to,  namely,  an  open  east  and  west 
course  through  the  coastal  plain  province,  a narrow  north  and  south 
portion  parallel  to  the  geological  structure  of  the  region,  and  a 
northeast  and  east-northeast  course  in  the  headward  portion.  In 
this  upper  part  the  basin  shows  the  same  feature  previously  noted  on 
the  Shaktolik,  namely,  that  the  tributaries  from  the  south  are  longer 
than  those  from  the  north,  so  that  the  basin,  if  the  main  stream 
be  considered  as  its  axis,  is  decidedly  unsymmetrical.  This  lack  of 
symmetry  seems  to  be  due  to  three  causes,  namely,  structural  con- 
trol, climatic  conditions,  and  tilting.  Asymmetrical  valleys  are 
common  in  Alaska,  and  have  previously  been  described  by  different 
authors.  An  epitome  of  the  various  causes  with  reference  to  a spe- 
cific region  has  been  published  by  Goodrich.0  It  was  pointed  out 
by  this  geologist  that  the  effect  of  insolation  differs  according  to  the 
condition  of  the  stream  as  to  load ; thus,  if  the  stream  is  overloaded, 
the  tendency  will  be  for  the  waste  to  push  the  stream  toward  the 
side  receiving  the  least  sun,  whereas,  if  the  stream  is  not  carrying  all 
the  material  it  can  the  reverse  tendency  will  dominate,  and  the 
stream  will  migrate  toward  the  side  receiving  the  most  sun.  Plate 
II,  A , shows  one  of  the  tributaries  of  the  Shaktolik  below  camp  A12, 
which  is  migrating  toward  the  north  because  the  stream  is  under- 
loaded  and  the  south-facing  slope  receives  more  warmth  than  the 

° Goodrich,  H.  B.,  Cause  of  asymmetry  of  streams : Eighteenth  Ann.  Kept.  U.  S.  Geol. 
Survey,  pt.  3,  1898,  pp.  285-289. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  II 


B.  UPLANDS  BETWEEN  EAST  FORK  AND  INGLUT  ALIK  RIVER. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


23 


other.  In  a consideration  of  the  development  of  the  drainage  it 
should  be  borne  in  mind  that  types  due  to  one  cause  alone  are  prac- 
tically absent  and  that  complexity  of  origin,  rather  than  simplicity, 
is  normal. 

From  Ungalik  River  passes  may  be  found  into  the  Inglutalik  to 
the  north  or  to  the  Kateel  on  the  east,  or  into  the  Shaktolik  on  the 
south.  None  of  these  passes  are  over  3,000  feet  above  the  sea,  and 
many  could  be  found  at  elevations  below  2,500  feet.  The  saddle  by 
which  McPherson  crossed  from  the  Kateel  to  the  Ungalik  was  only 
a little  over  2,000  feet. 


As  regards  size,  the  Ungalik  is  not  so  large  as  the  Shaktolik.  Two 
miles  below  camp  A1G  the  stream  could  be  crossed  in  less  than  2 
feet  of  water,  and  farther  upstream  it  was  still  shallower  except  for 
occasional  deep  holes.  Lower  downstream,  however,  in  the  coastal 
plain  portion  of  its  course,  it  becomes  deeper  and  sluggish,  and  in- 
stead of  a hard  grav- 
elly bottom  it  has  a soft 
mud  bottom  that  makes 
crossing  difficult  with- 
out a boat. 

Inglutalik  River  de- 
rives its  name  from  the 
Eskimo  words  meaning 
u river  of  bones,”  in  ref- 
erence to  the  number  of 

mastodon  and  other  „ , V/ZrJtJk 

Relatively  weak  rocl<s  Resi  stant  rocks 

bones  found  in  the  ter-  P]GCRE  2._Arrangfmt.nt  of  drainage  due  t0  geologic 
race  of  gravels  along  its  structure, 

course.  It  is  at  least  60  miles  long  and  appears  to  have  a greater 
volume  of  water  than  either  the  Shaktolik  or  the  Ungalik.  Below 
camp  A18,  in  the  coastal  plain  province,  the  river  can  not  be  forded ; 
at  camp  A18  is  the  first  riffle,  and  on  it  good  crossing  in  about  2 feet 
of  water  is  afforded.  Poling  boats  have  been  taken  as  far  as  camp 
B9,  and  during  seasons  of  normal  precipitation  could  undoubtedly  be 
worked  still  further  upstream. 

In  the  upper  part  of  the  Inglutalik  Basin  the  drainage  is  very  com- 
plex, and  many  readjustments  have  taken  place,  so  that  at  a distance 
of  5 or  6 miles  it  is  impossible  to  tell  whether  the  river  drains  toward 
the  north  or  the  south.  Backhand  or  barbed  drainage  is  common. 
It  should  be  noted,  however,  that  this  feature  is  not  always  to  be  ac- 
counted for  by  capturing,  but  in  many  instances  is  due  to  the  geo- 
logical structure.  Figure  2 indicates  in  diagrammatic  manner  how 
a normally  developed  subsequent  stream  (A)  may  have  a barbed 
junction  with  the  main  stream  without  capturing  having  taken 


24 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


place.  In  this  same  figure  stream  B is  also  a normally  developed 
subsequent  stream,  but  as  the  soft  bed  on  which  it  has  developed 
forms  an  acute  angle  with  the  course  of  the  main  stream  the  tribu- 
tary enters  without  the  barbed  junction. 

Low  passes  easily  traversed  by  horses  lead  from  the  Inglutalik 
into  the  Kateel  basin  to  the  northeast;  into  the  Ungalik  on  the  south; 
into  the  Koyuk  on  the  west ; and  into  the  Buckland  on  the  north.  It 
is  reported,  although  it  was  not  confirmed  by  personal  observation, 
that  part  of  the  Selawik  drainage  also  heads  against  the  Inglutalik. 
There  are  no  known  facts  which  would  make  such  a condition 
unlikely,  but  the  region  in  question  is  so  entirely  unexplored  that 
conjectures  as  to  the  drainage  are  hardly  warranted.  The  only 
information  on  this  subject  is  Zagoskin’s  trip  up  the  Kateel  to  near 
the  big  bend,  in  65°  30'  north  latitude.  According  to  this  traveler 
a low  pass  leads  from  near  this  point  northwest  to  the  Buckland.  It 
should  be  realized,  however,  that  Zagoskin  did  not  attempt  the  pas- 
sage; that  there  may  have  been  a misunderstanding  as  to  the  river 
on  the  western  side  of  the  divide,  and  that  it  is  possible  his  inform- 
ants were  not  correct  in  their  geography.  From  the  present  status 
of  knowledge  it  seems  more  likely  that  a pass  northwest  of  the  big 
bend  of  the  Kateel  would  lead  into  a north-flowing  branch  of  the 
Selawik  than  to  a west-flowing  branch  of  the  Buckland. 

KOYUK  RIVER. 

Koyuk  River  enters  the  northern  reentrant  of  Norton  Bay  and 
is  a river  over  80  miles  long.  For  the  first  15  miles  from  the  mouth 
it  has  a nearly  southerly  course,  but  above  this  point  it  flows  more  or 
less  directly  from  the  west  toward  the  east.  For  60  miles  or  so  its 
tortuous  meanders  make  measurements  along  the  river  many  times 
the  air-line  distance.  Mendenhall  and  Peters  in  1900  traversed  the 
river  as  far  west  as  the  head  of  canoe  navigation  a few  miles  above 
Knowles  Greek,  and  the  details  of  their  map  have  been  taken  for 
the  course  of  this  stream.  In  1903  ° Moffit  and  Witherspoon,  map- 
ping the  northeastern  part  of  Seward  Peninsula,  added  many  facts 
concerning  the  Koyuk  basin  north  of  the  main  stream  and  con- 
cerning the  river  itself  beyond  the  point  reached  by  Mendenhall 
and  Peters  in  1900.  . 

From  the  observations  of  the  earlier  geologists  and  topographers, 
supplemented  by  the  field  work  of  1909,  it  appears  that  the  Koyuk 
basin  is  unsymmetrical.  Of  the  various  tributaries,  East  Fork  un- 
doubtedly drains  the  largest  territory.  Its  basin  is  about  30  miles 
long,  heading  against  portions  of  Buckland  and  Inglutalik  river 
basins.  Many  low  passes  lead  from  the  East  Fork  basin  into  the 

“ Moffit,  F.  H.,  The  Fairhaven  gold  placers,  Seward  Peninsula  : Bull.  U.  S.  Geol.  Survey 
No.  247,  1905,  pis.  II  and  III. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


25 


Buckland.  Probably  the  lowest  pass  is  by  way  of  the  branch  on 
which  camp  B12  was  located.  The  elevation  of  this  camp  was  ap- 
proximately 300  feet  above  the  junction  of  East  Fork  and  the 
Koyuk,  and  as  there  is  a strong  upstream  current,  due  to  the  tides, 
as  far  as  the  mouth  of  Peace  River,  it  is  safe  to  assume  that  the 
mouth  of  East  Fork  is  practically  at  sea  level.  North  of  camp  B12 
there  is  a broad  abandoned  valley  in  which  there  are  several  lakes. 
Some  of  these  drain  northward  and  some  southward.  The  elevation 
of  these  lakes  is  not  more  than  100  feet  above  the  camp,  so  it  is 
certain  that  there  is  a route  across  Seward  Peninsula  from  Norton 
Sound  to  Kotzebue  Sound,  nowhere  more  than  400  feet  above  sea 
level. 

TRIBUTARIES  OF  NORTON  SOUND  WEST  OF  KOYUK  RIVER. 

West  of  Koyuk  River  the  main  tributaries  of  Norton  Sound  from 
east  to  west  are  Kwik,  Tubutulik,  Kwiniuk,  and  Fish  rivers.  All 
of  these  streams  are  mainly  within  the  area  occupied  by  metamorphic 
rocks  of  complex  structure  and  consequently  do  not  show  by  their 
courses  the  striking  structural  control  noted  in  the  rivers  farther 
east.  Because  of  the  greater  amount  of  information  available  con- 
cerning the  region  west  of  the  Koyuk,  the  map  of  southeastern  Sew- 
ard Peninsula  (PI.  I)  shows  the  distribution  and  character  of  these 
rivers  in  greater  detail  than  was  possible  on  the  smaller  scale  map 
adopted  for  the  Nulato-Norton  Bay  region  (PI.  V). 

Kwik  River  is  a small  stream  about  20  miles  long  flowing  in  the 
main  on  a very  flat  slope  in  a circuitous  course  in  a gravel-filled  basin. 
It  heads  in  the  divide  between  Norton  Bay  and  the  east- west  portion 
of  the  Koyuk.  Passes  lead  across  this  divide  at  low  elevations.  The 
lowest  pass  is  by  way  of  the  branch  on  which  camp  C4  was  located. 
At  this  point  a broad,  open  saddle  at  an  elevation  of  only  a little  more 
than  600  feet  affords  an  easy  route  from  one  basin  to  the  other.  The 
most  characteristic  feature  of  this  basin  is  the  flat  lowland  through 
the  lower  three-quarters  of  the  area  and  the  short,  rather  steep  gra- 
dients of  the  streams  above  the  point  where  they  enter  the  flats. 

Tubutulik  River  had  previously  been  traversed  by  Mendenhall  and 
Peters,  so  that  few  notes  concerning  the  stream  arrangements  were 
collected  in  1909.  In  the  main  this  basin  is  parallel  with  the  igneous 
intrusions  of  the  Darby  Range,  but  above  Lost  Creek,  where  the  gran- 
ites disappear,  the  course  for  several  miles  is  more  nearly  east  and  west. 
Above  this  point  its  general  direction  is  north  and  south.  In  this 
part  of  its  course  is  a lowland,  locally  known  as  Death  Valley,  which 
is  elliptical  in  outline  and  about  7 miles  long  by  5 miles  wide. 
North  of  Death  Valley  the  headwater  streams  rise  in  the  high  eastern 
extension  of  the  Bendeleben  Mountains  and  flow  on  steep  gradients 
into  the  Death  Valley  Basin.  The  lower  5 to  10  miles  of  the  Tubutulik 


26 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


basin  is  formed  by  swampy  lowlands  similar  to  those  at  the  mouth  of 
the  Kwik.  In  fact,  the  area  between  the  lower  portions  of  these 
streams  is  practically  undivided,  and  it  would  be  almost  impossible 
to  determine  just  what  portion  of  the  flat  was  tributary  to  one  stream 
and  what  to  the  other. 

Measured  in  a straight  line  from  its  head  to  its  mouth,  the  Tubu- 
tulik  is  about  40  miles  long,  but  its  numerous  meanders  make  the  dis- 
tance along  the  river  much  greater.  Several  low  passes  lie  between 
the  Tubutulik  and  the  Kwik  on  the  east,  the  Koyuk  on  the  north,  and 
the  tributaries  of  the  Fish  on  the  west.  The  ridge  between  the  Tubu- 
tulik and  the  Kwik  nowhere  exceeds  1,000  feet,  so  that  at  the  heads  of 
the  tributaries  are  many  places  where  passages  at  elevations  of  GOO  to 
800  feet  may  be  found.  Between  the  Tubutulik  and  the  Koyuk  there 
are  two  low  saddles  where  the  elevation  does  not  exceed  1,000  feet. 
The  most  important  of  these  saddles  is  the  one  east  of  Death  Valley, 
where  the  trail  from  Nome  to  Candle  crosses  the  divide.  At  this  place 
the  elevation  is  only  a little  more  than  800  feet  above  sea  level.  The 
low  saddle  is  north  of  the  north  fork  of  the  Tubutulik  and  leads  into 
Timber  Creek,  a tributary  of  the  Koyuk.  This  pass  is  broadly  open 
and  has  several  small  lakes  scattered  on  the  flat  divide.  Between  Tu- 
butulik and  Fish  rivers  there  are  two  or  three  low  passes,  but  the  one 
taken  advantage  of  by  the  telephone  lines  is  perhaps  the  lowest. 
North  of  this  one,  however,  near  camp  C8,  there  is  a saddle  at  an  ele- 
vation of  about  1,000  feet,  by  which  horses  can  easily  cross  from  the 
Tubutulik  into  the  Fish  River  basin. 

Southwest  of  the  Tubutulik  the  Kwiniuk  River  drains  an  area  of 
approximately  100  square  miles.  It  has  an  extremely  irregular 
course,  its  bends  in  the  main  being  dominated  by  the  general  north- 
south  geologic  structure.  It  has  many  side  streams  joining  it  in  back- 
hand manner.  This  is  especially  true  in  the  portion  around  camp 
C14.  About  2 miles  south  of  this  point  there  is  a long  tributary 
coming  in  from  the  west  which  makes  a sharp  bend  and  cuts  across 
the  prevailing  structure  to  join  the  Kwiniuk;  2 miles  north  of  camp 
C14  also  there  is  a stream  flowing  almost  due  south  until  it  enters  the 
northeastward-flowing  Kwiniuk.  It  is  believed  that  some  of  these 
abnormal  features  may  be  explained  by  the  obstruction  of  the  drain- 
age by  deposits  formed  by  valley  glaciers  from  the  Darby  Range, 
which  have  prevented  a former  direct  course  to  the  sea. 

The  Kwiniuk  basin  is  about  30  miles  long  and  is  on  the  whole 
rather  narrow.  In  places  rock  walls  constrict  the  river,  but  in  other 
places  there  are  gravel-filled  basins  of  small  extent  in  which  the  river 
splits  into  many  separate  channels.  At  the  mouth,  the  river  flows  on 
the  broad  gravel  deposits  (which  probably  represent  basin  filling) 
that  merge  wTith  the  flats  at  the  mouths  of  Tubutulik  and  Kwik 


NORTON  BAY-NULATO  REGION,  ALASKA. 


27 


rivers.  In  this  part  of  its  course  the  basin  is  characterized  by  an 
intricate  network  of  sloughs  and  channels  impossible  to  traverse 
in  summer. 

Fish  River  is  the  largest  stream  west  of  the  Koyuk.  Between  it 
and  the  Kwiniuk  many  streams  heading  in  the  north-south  Darby 
Range  flow  in  short  courses  eastward  into  Norton  Sound  or  westward 
into  Golofnin  Sound.  Fish  River,  like  the  Koyuk,  was  ascended  by 
Mendenhall  and  Peters  in  1900,  and  the  form  of  the  main  river  has 
been  taken  directly  from  their  map.  It  is  an  extremely  tortuous 
stream  in  its  lower  and  middle  course,  but  in  its  headward  part  and 
for  a short  distance  in  the  so-called  Fish  River  gorge  it  is  an  actively 
degrading  stream.  In  the  lower  part  the  river  splits  into  numerous 
distributaries  on  the  delta,  and  its  flow  is  so  sluggish  that  it  is  diffi- 
cult to  distinguish  the  main  channel  from  blind  sloughs.  Steam 
river  boats  ascend  the  river  as  far  as  White  Mountain,  but  above  this 
point  as  far  as  Council,  on  the  Niukluk,  or  as  far  as  Mosquito  Creek, 
on  the  main  river,  horse  boats  are  used. 

Above  the  junction  of  Niukluk  and  Fish  rivers  the  valley  of  the 
main  stream  is  constricted  and  the  river  flows  through  a gorge  with 
rather  steeply  sloping  walls  for  a distance  of  about  10  miles.  Up- 
stream from  the  gorge  the  valley  opens  out  and  the  floor  is  a flat 
gravel-covered  plain  15  miles  wide  parallel  with  the  direction  of  the 
stream  and  30  miles  long  transverse  to  this  direction.  This  part  of 
the  basin  is  an  unexplained  physiographic  feature.  The  plain  is 
dotted  with  lakes  and  sloughs  slightly  sunk  below  the  general  level 
of  the  surface.  Here  and  there,  irregularly  distributed,  are  low 
gravel  mounds  from  10  to  50  feet  in  height,  that  seem  to  mark  former 
deposits  so  dissected  that  perhaps  not  one-hundredth  of  their  original 
extent  is  preserved. 

The  main  tributaries  from  the  west  are  Niukluk  and  Pardon  rivers. 
The  former  rises  in  the  Bendeleben  Mountains  and  the  hills  to  the 
south  about  20  miles  west  of  the  mapped  area.  The  Pargon,  some- 
times incorrectly  called  the  Parantulik,  rises  in  the  high  east-west 
range  which  forms  the  eastern  extension  of  the  Bendeleben  Moun- 
tains. It  flows  along  the  southern  margin  of  the  Fish  River  basin 
for  nearly  20  miles  before  entering  the  main  stream.  From  the  east 
the  main  tributaries  of  Fish  River  are,  from  south  to  north,  Etchepuk 
and  Rathlatulik  rivers  and  Mosquito  Creek.  All  of  these  rise  in  the 
high  Darby  Range  that  forms  the  eastern  border  of  the  Fish  River 
basin.  In  their  headward  portions  they  all  flow  in  rather  youthful 
valleys  with  fairly  steep  gradients,  but  as  they  cross  the  flats  their 
slopes  decrease,  and  they  flow  in  sinuous  courses  slightly  incised 
below  the  level  of  the  plain. 


28 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


KOTZEBUE  SOUND  DRAINAGE. 

The  only  portion  of  the  Buckland  or  other  Kotzebue  Sound  drain- 
age seen  was  between  camps  B5  and  B13.  In  this  region  only  the 
headward  part  of  some  of  the  streams  belonging  to  the  Buckland 
were  observed  near  at  hand,  and  therefore  few  additional  data  as  to 
the  larger  features  of  the  basin  as  a whole  were  obtained.  It  seems, 
however,  that  the  area  of  this  basin  has  been  in  large  measure  ex- 
aggerated. From  the  mouth  of  the  Buckland  to  the  divide  between 
that  river  and  the  East  Fork  of  the  Koyuk  in  a straight  line  the  dis- 
tance is  between  50  and  60  miles,  and  from  the  mouth  to  the  divide 
near  camp  B5  is  only  a little  over  60  miles. 

Like  many  of  the  other  basins  which  have  been  carved  mainly  on 
bedded  sediments  of  Mesozoic  age  in  this  part  of  Alaska,  the  basin 
of  the  Buckland  tributary  streams  shows  pronounced  structural 
control.  This  results  in  an  irregular  distribution  of  narrow  valleys 
parallel  to  the  geological  structure  of  the  region,  with  transverse 
gorges.  In  this  kind  of  topography  the  recognition  of  the  true  direc- 
tion of  the  drainage  from  a distance  is  almost  impossible.  The  west- 
ern branch  of  the  Buckland,  visible  from  Bear  Creek  (north  of  camp 
B13)  flows  in  a broad,  flat  valley,  the  average  gradient  of  the  stream 
from  mouth  to  head  probably  not  exceeding  6 to  8 feet  a mile.  In 
the  descriptions  of  Quackenbush  ° and  of  the  earlier  surveys  by 
Captain  Ivellett  and  other  officers  of  H.  M.  S.  Herald  and  Plover , it 
is  stated  that  the  Buckland  is  navigable  in  light  boats  for  about  60 
miles  as  measured  along  the  river’s  course,  that  is,  as  far  as  the  forks 
of  the  stream  about  20  miles  north  of  the  Koyuk-Buckland  divide. 

The  low  pass  from  Buckland  to  the  east  fork  of  Koyuk  River 
has  already  been  described.  A pass  from  the  Buckland  into  the 
Kiwalik  basin  by  way  of  Bear  Creek  has  been  utilized  by  a road  from 
the  mining  camp  on  Bear  Creek  to  Candle.  The  divide  between  the 
Buckland  and  the  Inglutalik  is  low,  and,  although  usually  covered 
with  dense  brush,  it  offers  no  considerable  obstruction  to  crossing 
from  one  drainage  basin  into  the  other. 

UPLANDS. 

As  has  already  been  stated,  the  relief  in  the  Nulato-Council  region 
is  relatively  low.  Few  hills  are  more  than  3,000  feet  high,  and  the 
larger  part  of  the  upland  is  probably  not  more  than  2,000  feet  above 
sea  level.  There  are,  therefore,  but  small  differences  in  elevation  be- 
tween the  uplands  and  the  lowlands  and  still  less  between  different 
portions  of  the  upland.  This  results  in  producing  a sky  line  uninter- 
rupted by  any  considerable  inequalities. 

« Quackenbush,  L.  S.,  Notes  on  Alaskan  mammoth  expeditions  of  1907-8  : Bull.  Am.  Mus. 
Nat.  Hist.,  vol.  26,  1909. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


29 


Smooth,  rolling  uplands  are  particularly  characteristic  of  the 
East  Fork-Inglutalik  divide.  In  this  part  of  the  field  the  features 
are  slightly  dissected,  rounded  domes,  with  gentle  slopes  merging  with 
the  present  valley  walls  by  a series  of  benches.  Plate  II,  B (p.  22), 
shows  a typical  portion  of  this  upland  and  is  characteristic  in  a broad 
way  of  the  divides  between  most  of  the  minor  drainage  basins.  On 
such  uplands  traveling  is  good,  as  the  surface  is  well  drained  and  the 
frost-disintegrated  fragments  afford  good  footing.  Not  only  are  up- 
lands of  this  type  found  in  the  regions  where  unmetamorphosed  sedi- 
mentary rocks  form  the  bed  rock,  but  they  are  also  characteristic  of 
parts  of  the  schist  region — as,  for  instance,  at  the  head  of  Kwik 
Biver. 

Even  the  higher  and  more  rugged  divides  here  and  there  show 
a somewhat  flat-topped  character.  Thus,  on  both  sides  of  the  Koyuk- 
Buckland  lowland  there  are  numerous  flat-topped  hills,  some  a mile 
or  so  in  width,  carved  on  materials  very  different  both  in  composition 
and  in  apparent  resistance  to  weathering.  This  feature  is  also  seen 
in  the  hills  north  of  Death  Valley  on  the  Tubutulik.  On  one  of  these 
hills  north  of  camp  C7  a profile  similar  to  figure  3 was  observed  which 


a 1 Z Miles 


Figure  3. — Profile  of  hill  north  of  camp  C7,  at  head  of  Tubutulik  River. 

showed  at  least  five  flats  from  a quarter  to  half  a mile  wide.  These 
have  been  produced  on  a complex  structure  of  schists,  thin  limestones, 
and  granites. 

The  two  main  mountainous  regions  are  (1)  the  divide  between  the 
Yukon  and  the  Norton  Bay  drainages,  called  by  McPherson  the 
Brooks  divide,  and  (2)  the  Darby  and  Bendeleben  mountains.  In  the 
former  the  general  trend  is  north  and  south,,  with  the  highest  points 
only  little  more  than  3,000  feet  in  elevation  and  the  average  much 
less.  Conical  peaks  rising  500  to  800  feet  above  their  neighbors  afford 
easily  recognizable  landmarks,  visible  for  long  distances.  A few  steep, 
rocky  crags  were  seen,  but  all  are  easily  scalable.  In  the  Darby  and 
the  Bendeleben  mountains  the  trend  of  the  former  is  predominantly 
north  and  south  and  of  the  latter  east  and  west,  so  that  together  they 
form  a crescentic  highland  area.  The  crest  line  of  this  range  is 
ragged  and  irregular,  being  in  places  close  to  the  north  and  west  side 
of  the  range  and  at  others  close  to  the  south  or  east  side.  Here  and 
there  the  crest  line  is  so  narrow  that  passage  even  on  foot  is  hazardous, 
and  blocks  of  waste  disturbed  in  passing  roll  hundreds  of  feet  down 
the  slope  before  finding  lodgment.  This  is  true  particularly  of  the 
Bendeleben  Mountains,  where  glacial  action  of  the  alpine  type  has 


30 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


been  effective  in  the  past.  In  certain  parts  of  the  Darby  Range  also 
this  same  agency  has  produced  similar  uplands.  Plate  III,  A,  shows 
a portion  of  the  Darby  Range  much  dissected  by  glaciation  and  illus- 
trates the  narrow  pinnacled  character  of  the  upland  that  results. 
Such  divides  are  not  due  to  valley  glaciers  having  covered  the  upland, 
but  are  the  result  of  headward  erosion  on  opposite  sides  of  the  ridge. 

Regarding  the  origin  of  the  uplands,  there  has  been  no  clear  evi- 
dence found  to  indicate  the  effective  causes.  As  will  be  explained  in 
detail  later,  it  is  known  that  the  deformation  which  took  place  after 
the  deposition  of  the  Cretaceous  sediments  was  so  great  that  any 
topography  formed  prior  to  this  event  must  have  been  so  changed  as 
to  have  little  or  no  effect  on  the  present  topography.  The  surface 
therefore  has  been  formed  between  the  Eocene  and  the  present  time. 
It  is  known  that  none  of  the  mountains  indicated  by  the  dips  of  the 
strata  formed  by  the  folding  are  preserved  at  the  present  time  in  this 
region.  The  upland  surface  has  therefore  been  produced  by  erosion, 
and  the  present  hills  owe  their  height  rather  to  greater  resistance  to 
erosion  than  to  original  constructional  uplift.  Whether  this  erosion 
resulted  in  a nearly  plain  surface  approximately  at  sea  level,  which 
has  subsequently  been  uplifted  and  again  dissected,  or  whether  the 
erosion  took  place  at  considerable  elevations  above  sea  level  and 
leveled  without  base  leveling  the  tops  of  the  hills,  is  a question  that 
must  await  much  fuller  investigation.  There  are  the  following  ob- 
jections to  the  interpretation  that  the  present  upland  surface  repre- 
sents a formerly  nearly  base-leveled  surface  subsequently  uplifted — 
the  absence  of  any  water  formed  deposits  on  the  surface  of  the  up- 
land; the  lack  of  deep-rock  weathering;  the  number  of  flats  sepa- 
rated from  each  other  by  sharp  scarps  similar  in  all  characters  to  the 
uppermost  one,  which  require  similar  explanations;  the  absence  of 
drainage  arrangement  that  would  correspond  to  the  hypothetical 
earlier  surface ; the  indications  that  present-day  processes  are  respon- 
sible for  leveling  without  base  leveling.  On  the  other  hand,  the 
main  objection  to  the  idea  that  the  upland  does  not  mark  an  old 
erosion  surface  nearly  at  base  level  is  the  lack  of  known  processes 
capable  of  producing  a nearly  plain  surface  on  rocks  of  different 
resistances  to  erosion.  It  seems  wise  therefore  to  suspend  judgment 
as  to  the  origin  of  the  uplands,  as  further  information  is  required 
before  their  genetic  classification  can  be  effected. 

COASTAL  FEATURES. 

Soundings  made  by  the  Coast  and  Geodetic  Survey  ° and  others 
have  shown  that  nowhere  in  Norton  Bay  and  Sound  within  the  areas 
represented  on  Plates  I and  V is  there  a depth  of  water  exceeding 

° See  chart  9380  of  the  Coast  and  Geodetic  Survey,  edition  of  1908. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  III 


B.  EAST  COAST  OF  DARBY  PENINSULA. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


31 


100  feet,  and  over  much  of  this  water  area  the  depth  averages  about 
50  feet.  In  general  the  5-fathom  line  lies  several  miles  from  the 
coast,  so  that  vessels  find  no  harbors  and  have  to  discharge  cargoes 
on  lighters.  A few  exceptions  to  this  rule  occur,  most  notably  along 
the  east  side  of  the  Darby  Peninsula  and  at  Golofnin  Sound.  At  the 
former  locality  the  coast  is  rocky  and  landing  places  for  vessels  of 
sea-going  size  are  wanting.  Plate  III,  B , shows  a typical  portion  of 
the  eastern  coast  with  the  waves  beating  directly  on  the  cliffs  and 
with  a beach  so  slightly  developed  that  it  is  impossible  for  a man  to 
wTalk  around  the  shore.  With  such  topography  it  is  evident  that 
shelter  for  vessels  is  wanting. 

Golofnin  Bay,  on  the  other  hand,  presents  a fairly  good  harbor  for 
vessels  drawing  less  than  20  feet,  as  it  is  sheltered  by  high  hills  from 
the  strong  winds.  The  channel,  however,  is  crooked  and  the  bay  is 
constantly  filling  up  with  the  detritus  brought  down  by  Fish  Kiver. 
Ocean-going  vessels  from  Seattle  call  at  this  place  irregularly  during 
the  season  and  discharge  cargoes  near  the  mission  on  lighters.  With- 
out recourse  to  dredging,  however,  this  harbor  would  be  of  slight  value 
in  the  general  economic  development  of  the  region.  It  is,  moreover, 
some  distance  from  the  productive  gold  areas  and  so  is  not  much  used, 
although  during  the  boom  days  of  the  Council  region  it  gave  prom- 
ise of  being  important  and  even  now  it  is  the  gateway  by  which  most 
of  the  supplies  for  Council  and  vicinity  enter  the  country. 

Kotzebue  Sound  on  the  northern  shores  of  Seward  Peninsula  is 
also  a relatively  shallow  sea,  few  if  any  places  having  a depth  of 
100  feet.  One  of  the  latest  'incidents  in  the  geology  of  the  region 
was  a slight  depression  of  the  land,  so  that  the  submerged  lower 
courses  of  some  of  the  larger  streams  afford  shelter  for  light-draft 
vessels.  The  shallowness  of  the  basin  as  a whole  and  the  crooked  and 
constantly  changing  channels  leading  to  these  harbors  make  naviga- 
tion difficult. 

Tides  in  Norton  Sound  are  relatively  slight  in  their  range  but  in- 
crease toward  the  bay  heads.  No  accurate  measurements  of  the  tides 
have  been  made  in  this  part  of  the  region,  and  as  the  wind  has  a con- 
siderable effect  on  the  change  of  water  surface  it  is  impossible  to  make 
any  short-period  observations  of  value.  It  is  probable,  however,  from 
determinations  made  at  Nome,  that  the  tides  seldom  have  a range  of 
more  than  2 feet  along  the  east  side  of  Darby  Peninsula.  Judged 
by  the  way  in  which  the  Koyuk  was  backed  up  by  the  tide  near  camp 
A20  the  tidal  range  near  the  head  of  Norton  Bay  probably  exceeds 
3 feet. 

As  has  been  already  noted,  lagoons  are  found  along  portions  of 
Norton  Sound.  These  owe  their  formation  mainly  to  shore  currents 
blocking  the  mouths  of  streams.  Sand  reefs,  such  as  occur  near  Sol- 
omon and  at  many  other  places  in  western  Seward  Peninsula,  are 


32 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


absent  in  the  area  studied.  Many  of  the  lagoons  are  filled  with  drift 
timber,  a good  deal  of  which  has  doubtless  been  brought  down  by 
the  Yukon  and  cast  upon  the  shore  by  the  currents. 

The  currents  are  complex  and  have  been  determined  mainly  by 
the  effect  they  have  exerted  on  the  land  forms.  Near  the  mouths  of 
the  Kwiniuk  and  the  Tubutulik  the  long  spits  with  their  free  ends 
pointing  east  give  clear  evidence  that  the  currents  there  are  flowing 
from  west  toward  the  east,  but,  south  of  camp  C1T  for  4 or  5 miles 
the  apparent  direction  is  southwest.  At  Carson  Creek,  however,  the 
general  direction  seems  to  be  northeast.  On  the  east  side  of  Norton 
Bay,  near  the  mouth  of  the  Inglutalik,  the  shore  forms  seem  to  have 
been  made  by  currents  flowing  toward  the  north,  whereas  near  Island 
Point  the  dominant  current  seems;  to  divide,  the  southern  part  flow- 
ing southward  and  the  northern  part  northeastward.  From  the 
south  end  of  the  Reindeer  Hills  the  long  south-pointing  sand  spit 
seems  to.  show  that  the  direction  of  currents  there  is  in  general 
southward. 

VEGETATION  AND  GAME. 

As  the  main  object  of  the  expedition  of  1909  was  to.  acquire  infor- 
mation concerning  the  geology  of  the  region  traversed,  little  atten- 
tion was  paid  to  extraneous  matters.  A few  notes  on  the  general 
character  of  the  vegetation  and  game  may,  however,  be  included. 

Of  the  evergreen  trees  spruce  is  the  only  one  of  sufficient  impor- 
tance to  be  considered.  The  trees  seen  probably  average  10  to  12 
inches  in  diameter.  Spruce  extends  as  far  west  as  Council,  but  beyond 
this  point  is  practically  wanting.  In  the  eastern  part  of  the  area, 
near  the  Yukon,  it  grows  at  elevations  close  to  2,000  feet,  but  far- 
ther west,  toward  Norton  Bay,  at  lower  elevations,  so  that  west  of 
the  Brooks  divide  it  is  seldom  found  above  1,000  feet.  West  of 
the  Koyuk  it  rarely  is  found  above  800  feet,  and  only  in  the  valleys 
along  the  streams.  In  the  western  part  of  the  Fish  River  drain- 
age basin,  spruce  does  not  grow  on  any  of  the  streams  north  of 
Mosquito  Creek.  Spruce  is  found  along  the  eastern  coast  of  Darby 
Peninsula  up  to  elevations  of  about  800  feet,  but  west  of  the  range  it 
seldom  grows  at  more  than  500  feet  above  the  sea.  Plate  IV  shows 
the  general  distribution  of  timber  in  the  region. 

Birch,  used  by  the  natives  for  sled  frames  and  similar  gear,  is 
found  in  many  places  in  the  Yukon  basin,  but  it  gradually  disappears 
farther  west  until  the  last  birch  seen  on  the  Koyuk  was  near  Kenwood 
Creek  and  the  last  sizable  trees  in  the  Darby  Peninsula  were  on  the 
eastern  slopes  of  Mount  Kwiniuk  and  on  the  lower  slopes  of  Mount 
Kwiktalik  or  Haystack  Mountain.  While  birch  is  found  in  the  Yukon 
basin,  but  does  not  occur  notably  to  the  west  of  this  area.  The  Seward 
Peninsula  birches  are  the  yellow  and  the  black  birch.  The  low  pros- 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  IV 


10 o io  zo  jo  Miles 


MAP  SHOWING  DISTRIBUTION  OF  TIMBER. 


NORTON  BAY  NULATO  REGION,  ALASKA. 


33 


trate  birch,  which  has  little  or  no  fuel  value,  is  much  more  widely 
distributed  and  can  be  found  throughout  Seward  Peninsula. 

Willows  are  common  along  almost  all  the  Seward  Peninsula 
streams.  The  willows  are  of  several  different  kinds,  from  prostrate 
varieties  to  trees  8 or  10  feet  in  height,  the  latter  being  the  main 
source  of  fuel  throughout  the  western  portion  of  southeastern  Seward 
Peninsula.  Alders  are  most  numerous  along  the  eastern  shore  of  the 
Darby  peninsula,  where  they  form  a dense  undergrowth  of  half  re- 
cumbent interlocking  branches,  through  which  passage  can  be  effected 
only  by  chopping  a trail. 

No  statement  of  the  vegetation  would  be  characteristic  without 
mention  of  the  abundant  berries,  which  grow  mainly  above  the  tree 
zone.  Blueberries  are  particularly  prolific,  the  low  bushes  forming 
in  places  a mat  of  vegetation.  Salmon  berries,  much  prized  by  na- 
tives and  prospectors,  grow  under  essentially  the  same  conditions  as 
blueberries  and  are  especially  abundant  on  rolling  low  uplands,  such 
as  those  between  the  Buckland  and  East  Fork  of  Koyuk  River.  Cur- 
rants are  found,  but  are  not  abundant. 

Several  kinds  of  grasses  and  forage  for  horses  are  found  and  are 
generally  sufficiently  plentiful,  so  that  they  do  not  have  to  be  specially 
sought  until  late  in  the  season.  The  pack  horses  used  by  the  Survey 
party  were  particularly  fond  of  the  so-called  “ goose  grass,”  a kind 
of  equisetum  that  grows  on  well-drained  areas  near  the  banks  of  the 
streams  where  trees  do  not  form  a thick  shade.  By  the  first  of  Sep- 
tember frosts  so  impair  the  vitality  of  the  grasses  that  forage  must 
be  sought  with  care  in  the  protected  valley  heads  facing  south,  and 
it  becomes  necessary  to  place  camp  with  considerable  thought  as  to 
the  feed  supply. 

Flowers  are  abundant  and  give  brilliancy  to  the  landscape  in  the 
spring  and  summer.  Some  fifty  varieties  were  noted,  but  no  collec- 
tions were  made,  and  therefore  no  specific  determinations  were  pos- 
sible. The  general  impression,  however,  was  that  flowers  were 
abundant,  but  that  they  were  limited  to  relatively  few  genera  and 
families. 

Birds  and  animals  are  fairly  abundant  throughout  the  region, 
although  they  are  not  so  plentiful  that  game  can  be  relied  on  for 
food.  In  the  higher  hills  between  the  Yukon  and  Norton  Sound 
numerous  caribou  signs  showed  that  the  mosquitoes  had  driven  these 
animals  into  the  highlands  during  the  early  part  of  the  summer. 
Farther  west  caribou  are  almost  entirely  wanting,  although  probably 
a few  may  still  be  found  in  the  unfrequented  region  north  of  the 
Koyuk.  Domesticated  reindeer,  held  either  by  government  or  pri- 
vate ownership,  are  herded  near  the  mouth  of  the  Shaktolik  and  south 
of  Cheenik.  These  herds  are  moved  from  place  to  place,  and  some  - 
times the  animals  stray  away  and  become  wild. 

71469°—  Bull.  449—11 3 


34 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


Bears  are  comparatively  numerous  in  the  less  frequented  parts  of 
the  region.  AVell-trodden  bear  trails  run  along  the  Shaktolik  for 
many  miles,  where  the  animals  fish  during  the  salmon  season.  Along 
the  ridge  between  Kwik  and  Tubutulik  rivers,  also,  bear  signs  are 
abundant,  especially  while  the  blueberries  are  ripe.  In  the  upper 
part  of  the  Kwiniuk  basin  near  camp  C14  the  sand  bars  are  covered 
with  bear  trails.  From  the  reports  of  prospectors  and  trappers  it 
is  said  that  most  of  the  bears  are  rather  large  and  brown,  few  black 
bears  being  found.  The  only  bear  that  was  seen  by  the  Survey  party 
was  a very  light  brown. 

Caribou  and  bear  are  the  only  two  large  animals  in  the  region  but 
there  are  several  small  animals  that  are  caught  either  for  their  fur 
or  as  food.  A few  rabbits  are  found  in  Seward  Peninsula,  but  none 
wrere  seen  in  the  Nulato-Norton  Bay  region.  Red  foxes  were  seen, 
and  cross  foxes  are  reported.  Some  marten,  muskrat,  and  other 
small  skins  are  taken  by  trappers  in  the  Yukon  basin  contiguous  to 
Nulato,  but  the  number  of  skins  is  yearly  decreasing.  Porcupine 
were  seen  in  the  Inglutalik  and  Tubutulik  river  basins.  Ground 
squirrels  common  in  the  less-forested  regions  of  Seward  Peninsula 
are  almost  entirely  absent  throughout  the  greater  part  of  the  area 
east  of  the  Koyuk  River. 

Of  the  birds,  ptarmigan  are  perhaps  the  most  abundant  throughout 
the  region  as  a whole,  but  they  are  seldom  found  near  the  coast  and 
are  yearly  becoming  fewer  and  fewer.  Early  in  the  season  these 
birds  are  found  hiding  in  the  brush  with  their  young,  but  later  in 
the  summer  flocks  of  fifteen  or  so  may  be  flushed  in  many  of  the 
blueberry  patches.  After  the  berries  begin  to  fail  and  cold  weather 
approaches,  the  ptarmigan  move  from  the  higher  land  and  congre- 
gate on  the  sand  bars  of  the  streams.  A little  later  they  begin  to 
gather  into  the  large  coveys  so  often  seen  after  the  snow  has  begun 
to  fall. 

Along  the  coast  where  ponds  and  lagoons  occur  ducks,  geese,  and 
other  water  fowl  are  plentiful.  The  southward  migration  of  the 
geese  in  1909  took  place  the  last  of  August  and  the  first  of  September, 
and  during  this  time  thousands  of  birds  passed  over  Norton  Bay. 
Cranes  were  seen,  some  living  on  the  low  swampy  country  of  the 
coastal  plain  province  and  others  apparently  making  their  homes  on 
the  dry  rolling  uplands.  Robins,  crows,  and  many  other  birds  living 
in  more  southern  regions  were  also  observed  but  not  minutely  noted. 
Owls,  both  barred  and  snowy,  are  common,  and  their  regurgitations 
may  be  found  on  almost  every  knob  that  gives  a lookout  over  the 
surrounding  country.  A few  eagles  and  hawks  were  seen.  Spruce 
or  “ fool  ” hens  were  especially  noted  in  the  Darby  peninsula  country 
south  of  the  mouth  of  the  Kwiniuk,  but  they  are  also  found  in  many 
other  parts  of  the  region. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


35 


Fish  are  almost  always  plentiful  and  can  be  relied  on  by  travelers 
for  food.  Grayling  are  the  most  common  of  the  fish  and  are  found 
in  all  streams  of  sufficient  size.  In  length  they  range  from  a few 
inches  to  about  20  inches.  They  will  take  a fly  hook  at  almost  all 
times  during  the  summer.  Trout  of  several  varieties  live  in  the  clear 
swift  waters  of  the  mountain  streams  and  may  be  caught  with  a fly 
hook.  Salmon  usually  run  up  the  larger  streams  and  are  much  used 
for  food  by  trappers,  prospectors,  and  natives  for  themselves  and 
their  dogs.  Salmon  were  seen  on  the  Inglutalik  as  far  upstream  as 
camp  B9,  on  the  Koyuk  above  East  Fork,  on  the  Kwiniuk  above 
camp  C14,  and  on  the  Niukluk  far  above  Council.  The  season  of 
1909,  however,  was  a particularly  poor  salmon  season,  and  only  a 
few  fish  were  caught  in  any  of  the  Norton  Bay  streams  considered  in 
this  report. 

Salt  water  forms  of  life  are  abundant  in  Norton  Bay  and  are  used 
for  food  and  clothing.  The  tomcod,  a small,  bony  fish,  and  the  her- 
ring are  caught  by  natives  and  whites.  From  the  fur  of  the  hair 
seal  much  of  the  clothing  of  the  natives  is  made,  and  the  skin  of  the 
oogruk,  a thick-skinned  seal,  furjiishes  almost  all  of  the  homemade 
footwear  (the  mukluk)  of  the  inhabitants.  Walrus  is  sometimes 
caught  near  the  edge  of  the  ice  pack  in  the  spring,  and  its  flesh  is  used 
for  food. 

CLIMATE. 

Continuous  records  of  the  various  elements  of  climate  have  not 
been  made  in  any  part  of  the  region  for  sufficient  length  of  time  to 
afford  accurate  data  for  describing  the  prevailing  conditions.  The 
nearest  observation  stations,  at  Nome  and  at  St.  Michael,  are  both 
situated  on  the  coast  and  give  but  little  information  concerning  the 
interior.  At  present,  therefore,  there  are  few  records  available  for 
the  Nulato-Council  region  except  scanty  observations  extending  over 
only  short  periods. 

TEMPERATURE. 

At  Nome  the  highest  temperature  recorded  during  1909  was  70°  F., 
but  it  is  probable  that  in  the  interior,  where  the  temperature  is  not  so 
much  affected  by  the  sea,  higher  records  would  have  been  obtained. 
The  work  of  the  Survey  party  was  carried  on  in  the  higher  hills  dur- 
ing the  hottest  part  of  the  summer,  so  that  the  temperatures  were 
much  lower  than  they  would  have  been  near  sea  level.  Ice  one-quarter 
of  an  inch  thick  formed  on  water  in  a pail  during  the  night  of  July 
24  at  an  elevation  of  about  1,500  feet  at  camp  B5.  On  August  5 ice 
remained  on  the  small  pools  of  water  along  Peace  River  at  an  eleva- 
tion considerably  less  than  1,000  feet  until  after  10  a.  m.  The  hills 
north  of  Mosquito  Creek  and  the  head  of  the  Fish  River  valley  were 


36  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

heavily  covered  by  snow  on  September  1,  and  on  September  16  snow 
covered  the  ground  down  to  800  or  900  feet  on  the  southern  end  of  the 
Darby  Range  and  remained  on  hills  above  1,000  feet  for  the  rest  of 
the  season. 

The  mean  annual  temperature  at  Nome  for  1907  was  24°  F.,  and 
for  1908  it  was  25°  F.  As  it  seems  fully  as  warm  at  Nome  as  in  the 
region  to  the  east  at  the  same  time,  it  is  probable  that  the  mean  an- 
nual temperature  is  not  far  different  for  the  two  localities.  The  sum- 
mer temperatures  are  higher  in  Nulato-Council  region  because  of  the 
absence  of  sea  control,  which  would  also  make  the  winter  tempera- 
tures lower,  so  that  these  two  factors  would  tend  to  balance  each 
other.  Further  data  on  the  temperatures  are  afforded  by  a few  ob- 
servations made  at  Nulato  and  at  the  Omilak  silver  mine,  and 
published  by  Abbe.® 


Extreme  ranges  in  temperature  ( °F .)  at  Nulato  and  at  Omilak  mine,  Alaska. 


Jan. 

Feb. 

Mar. 

Apr. 

May. 

Oct. 

Nov. 

Dec. 

Nulato: 

Maximum 

23 

29 

44 

50 

71 

47 

28 

31 

Minimum 

-62 

-60 

—33 

—23 

7 

-13 

-36 

—54 

Omilak  mine: 

Maximum 

43 

36 

43 

55 

63 

36 

32 

Minimum 

-33 

-52 

-36 

-24 

16 

- 2 

-29 

-29 

The  observations  at  Nulato  from  which  this  table  was  compiled 
were  carried  on  for  12  months,  from  October,  1894,  to  May,  1895, 
and  from  January  to  April,  1896;  those  at  Omilak  mine  were  also 
carried  on  for  12  months,  from  January  2 to  May,  1884,  from  Oc- 
tober 18  to  December,  1884,  and  from  January  to  April  16,  1885.  In 
the  report  it  is  noted  that  in  the  fall  of  1894  the  Yukon  was  closed  at 
Nulato  on  October  16,  and  opened  in  the  spring  of  1895  on  May  22. 
Near  Omilak  mine,  Fish  River  opened  on  May  21,  and  was  closed 
by  ice  on  September  25,  1884;  in  1885  this  riv#er  opened  on  May  9. 

Dall,* &  who  spent  a winter  at  Nulato,  has  published  the  following 
table  of  temperatures  for  the  different  seasons  at  that  place : 


Range  of  temperature  at  Nulato,  Alaska,  by  seasons. 


Spring  _ 
Summer 
Fall  ___ 
Winter. 


° F. 
29.3 
60.0? 
36.0? 
—14.0 


Year 


'27.8 


PRECIPITATION. 

During  the  summer  of  1909  the  precipitation  in  the  western  part 
of  Seward  Peninsula  was  abnormally  low,  and  it  seems  probable  that 


a Abbe,  Cleveland,  jr.,  Prof.  Paper  U.  S.  Geol.  Survey  No.  45,  1906,  pp.  133-200. 

6 Dali,  W.  H.,  Alaska  and  its  resources,  p.  436. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


37 


the  amount  of  rain  received  by  the  Nulato-Norton  Bay  region  was 
also  less  than  usual.  There  were  less  than  a dozen  really  rainy  days 
from  the  latter  part  of  June  to  the  end  September,  but  in  this  period 
there  were  38  days  on  which  it  showered. 

The  following  table  gives  the  results  of  previous  instrumental 
observations  at  Nulato  and  at  the  Omilak  silver  mine.® 


Mean  precipitation,  including  melted  snow  and  mean  number  of  days  with  days 
with  0.01  inch  or  more  precipitation  at  Nulato  and  Omilak  mine,  Alaska. 


Jan. 

Feb. 

Mar. 

Apr. 

May. 

Oct. 

Nov. 

Dec. 

Nulato: 

Mean  total 

Davs. . „ 

0.68 

5 

0.91 

7 

1.46 

12.5 

0. 16 
2 

0. 36 
4 

1.  36 
8 

1.20 

6 

1.42 

8 

Omilak 

Mean  coca*  

Days . . . 

0.40 

3 

0. 32 
3 

0. 15 
3.5 

0. 07 
4 

0.02 

2 

0.23 

0. 45 
3 

0. 18 
3 

The  record  for  Nulato  was  for  10  months,  from  October,  1894,  to 
May,  1895,  and  from  January  3 to  March,  1896;  the  record  for 
Omilak  mine  was  for  9J  months  from  February  to  May  and  from 
October  18  to  December,  1884,  and  from  January  to  March,  1885. 

From  what  is  known  of  near-by  areas,  it  may  be  stated  that  the 
amount  of  precipitation  during  the  8 winter  months  is  roughly  be- 
tween one-half  and  one.- third  of  the  total  for  the  year.  If  a factor 
of  this  value  be  applied  to  the  tables  so  as  to  correct  the  total  for 
the  year  on  the  basis  of  the  entire  12  months,  it  follows  that  the 
annual  precipitation  at  Nulato  is  between  15  and  20  inches  and  from 
10  to  12  inches  at  Omilak  mine.  This  would  make  the  Fish  River 
region  about  equivalent  in  moisture  to  the  region  near  Nome  and 
the  region  around  Nulato  much  more  moist.  The  region  as  a whole, 
however,  would  be  classed  as  semiarid  and  similar  to  a large  part 
of  the  States  of  Montana,  Idaho,' Wyoming,  and  Colorado.  As  the 
larger  part  of  the  precipitation  comes  from  June  to  September,  the 
impression  gained  by  a summer  traveler  is  of  a region  of  much 
greater  rainfall  than  is  actually  the  case. 

WIND. 

Throughout  the  region  the  northerly  winds  are  the  fair  weather 
winds,  whereas  those  from  the  south  usually  bring  rain.  During 
1909  the  predominant  wind  direction  was  from  the  north,  and  the 
weather  was  accordingly  dry  for  the  greater  part  of  the  time.  Owing 
to  the  absence  of  a heavy  cover  of  vegetation  over  most  of  the  upland 
area,  the  force  of  the  winds  is  strong  and  the  effects  are  marked.  On 
the  bare  limestone  hills  pieces  of  detritus  are  moved  by  the  wind,  and 
the  small  sand  grains  are  quickly  removed  from  the  places  where 


Abbe,  Cleveland,  jr.,  op.  cit.,  pp.  162-165. 


38 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


they  are  formed  by  disintegration.  In  many  places  the  foliage  on  the 
lower  lands  is  covered  with  the  wind  transported  dust. 

Dust  whirls  caused  by  convectional  currents  of  air  induced  by 
overheating  the  lower  layers  were  seen  several  times  along  river  bars. 
One  such  whirl  started  on  the  Shaktolik  River  with  such  explosive 
violence  that  it  threw  up  sun-baked  pieces  of  mud  several  inches  in 
diameter  and  scooped  out  a shallow  depression.  Several  dust  whirls 
were  noted  on  the  lower  part  of  East  Fork  and  Koyuk  rivers  and 
could  be  traced  for  several  miles  across  country. 

SETTLEMENTS  AND  POPULATION. 

The  only  villages  in  the  Nulato-Council  region  are  Nulato,  Kaltag, 
Cheenik,  Bluff,  and  Council.  Road  houses  are,  however,  numerous 
along  the  coast  and  form  a complete  line  from  east  to  west.  During 
the  summer  there  is  but  little  travel,  but  during  the  winter  the  mail 
and  travelers  furnish  patronage  to  road  houses  along  the  coast  at 
Carson  Creek,  Walla  Walla,  Kuiuktulik,  Miniatulik,  Moses  Point, 
Isaacs  Point,  Ungalik  River,  and  Shaktolik  River.  Along  Fish 
River  there  are  road  houses  between  Cheenik  and  Council,  at  the 
mouth  of  Fox  River,  and  at  the  mouth  of  the  Niukluk.  On  the 
Yukon  River  are  numerous  road  houses  from  Kaltag  eastward. 

A few  scattered  cabins  are  the  only  other  habitations  in  the  region, 
and  these  are  occupied  but  a short  time  each  year,  mainly  by  trap- 
pers. On  the  lower  part  of  the  Inglutalik,  6 or  8 miles  from  the 
coast  and  on  this  same  stream  near  camp  B7,  are  cabins  of  this  sort. 

The  mining  and  prospecting  centers  of  settlements  are  principally 
in  the  vicinity  of  Bluff  and  Council  on  Ophir,  .Melsing,  Mystery, 
and  Goldbottom  creeks.  There  are  several  cabins,  however,  on 
Bonanza  Creek  occupied  by  placer  miners  who  hold  ground  on  this 
stream.  At  the  Omilak  silver  mine  on  Omilak  Creek,  a tributary  of 
Fish  River,  a mining  camp  has  been  established  since  the  early 
eighties  and,  although  now  practically  abandoned,  at  different  times 
has  had  more  than  a score  of  inhabitants.  On  Bear  Creek,  a tribu- 
tary of  the  Buckland  from  the  west,  there  has  been  a small  settle- 
ment of  placer  miners  since  1902.  Two  cabins  near  Alameda  Creek, 
a tributary  of  Koyuk  River  from  the  west,  mark  a small  placer  set- 
tlement. Ditch  camps  with  one  or  two  men  each  have  been  estab- 
lished along  the  Candle  ditch  line  on  Kiwalik  River,  but  are  vacant 
during  the  winter. 

Native  encampments  are  found  principally  along  the  coast  and 
belong  almost  entirely  to  Eskimos.  Along  the  Yukon  are  Indian 
villages,  generally  established  on  the  outskirts  of  the  white  men’s 
villages.  The  Indians,  as  a rule,  have  a more  or  less  permanent 
abode,  but  the  Eskimos  migrate  along  the  coast  and  are  seldom  found 
several  seasons  in  the  same  place.  There  is  an  exception,  however, 


NORTON  BAY-NULATO  REGION,  ALASKA.  39 

in  the  case  of  those  owning  reindeer.  These  people  usually  summer 
in  nearly  the  same  place,  but  during  the  fall  and  winter  they  are  con- 
stantly moving  their  herds  from  one  pasture  ground  to  another.  The 
largest  reindeer  settlements  are  near  Shaktolik  and  Cheenik,  where 
the  Government  herds  are  located.  These  herds  are  mainly  tended 
by  natives. 

No  attempt  was  made  to  obtain  a count  of  the  population,  but,  from 
the  best  estimates  it  has  been  possible  to  make,  it  is  probable  that 
there  are  between  1,000  and  1,500  whites  and  natives  in  the  Nulato- 
Council  region. 

DESCRIPTIVE  GEOLOGY. 

In  the  Nulato-Council  region  there  are  two  major  geologic  prov- 
inces, namely,  the  Cretaceous  basin  and  its  inclosing  rim.  In 
the  mapped  area  only  portions  of  the  western  borders  of  the  basin 
were  studied,  and  neither  the  northern  nor  the  southern  boundaries 
were  determined.  In  the  Cretaceous  areas  only  exploratory  surveys 
were  made,  and  the  eastern  rim  was  not  visited  by  the  party  of  1909. 
By  reason,  therefore,  of  the  relatively  slight  amount  of  geologic  in- 
formation, this  field  is  shown  on  the  comparatively  small  scale  map, 
Plate  V (in  pocket),  of  the  Nulato-Norton  Bay  region.  Farther 
west,  however,  the  previous  work  of  Mendenhall,  Moffit,  Collier, 
Brooks,  and  Richardson,  supplemented  by  the  surveys  of  1909,  has 
warranted  publication  on  the  larger  scale  of  Plate  VI  (in  pocket), 
the  geologic  map  of  southeastern  Seward  Peninsula.  It  should  be 
pointed  out  that  neither  map  presents  the  details  of  the  geology,  for 
there  are  many  problems  which  must  await  much  more  searching 
investigation  than  the  hasty  trip  of  1909  would  permit. 

The  rocks  or  deposits  of  the  region  may  be  assigned  to  six  main 
groups — the  undifferentiated  metamorphic  rocks  mainly  of  pre- 
Silurian  age,  the  Paleozoic  rocks,  the  Cretaceous  sedimentary  rocks, 
the  igneous  rocks  mainly  pre-Cretaceous  but  in  part  later  than 
that  period,  the  veins,  and  the  unconsolidated  deposits  mainly  of 
Quaternary  age.  Each  group  shows  individual  characters  which  are 
described  in  the  following  pages  and  the  areal  distribution  is  indi- 
cated on  the  geologic  maps,  Plates  Y and  YI.  Plate  VI  is  the  more 
serviceable  for  showing  the  distribution  of  the  metamorphic  and 
igneous  rocks,  and  Plate  Y for  showing  the  nonmetamorphic  consoli- 
dated sediments,  but  both  maps  are  necessary  for  a complete  idea  of 
the  areal  extent  of  the  different  geologic  members. 

UNDIFFERENTIATED  METAMORPHIC  ROCKS. 

The  greater  part  of  southeastern  Seward  Peninsula  and  the  south- 
eastern part  of  the  Nulato-Norton  Bay  region  are  formed  of  a series 
of  metamorphic  rocks,  much  folded,  sheared,  and  so  changed  that 


40 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


in  but  few  places  are  their  original  characters  preserved.  This  com- 
plex consists  of  a variety  of  different  rocks  grouped  on  the  basis  of 
structure  or  lithology  as  schists,  limestones,  and  quartzites. 

AREA  EAST.  OF  THE  YUKON. 

The  eastern  area  of  metamorphic  rocks  has  not  been  studied  in  de- 
tail, but  the  following  quotation  from  Maddren  a will  serve  to  describe 
the  general  lithology: 

The  oldest  group  of  sedimentary  rocks  consists  of  the  quartzite  and  mica-quartz 
schists,  with  associated  crystalline  limestones,  garnet  schists,  and  fine-textured 
slaty  schists  or  phyllites  that  form  a large  part  of  the  Kaiyuh  Mountains  and  ex- 
tend northeastward  across  the  Yukon  to  the  basin  of  Tozitna  River  and  possibly 
south  westward  to  the  Haiditarod.  Succeeding  this  belt  of  schistose  sediments 
is  an  extensive  group  of  ancient  diabasic  effusive  rocks  that  appear  to  be 
stratigraphically  associated  with  the  schistose  rocks.  These  diabasic  rocks 
have  not  been  deformed  nearly  so  intensely  as  the  schistose  group.  In  places 
they  show  greenstone  schist  phases,  but  for  the  most  part  they  have  not  been 
greatly  altered.  Their  contact  relations  to  the  schists  are  not  known  in  this 
region.  They  appear  to  flank  both  the  northwest  and  the  southeast  sides  of  the 
schist  belt  in  the  Kaiyuh  Mountains,  where  they  extend  southwestward  to  the 
Innoko,  and  they  have  extensive  development  toward  the  northeast  north  of  the 
Yukon  as  far  as  Gold  Mountain  and  beyond.  No  statement  as  to  the  thickness 
of  this  diabasic  group  can  be  made  at  present. 

SOUTHEASTERN  SEWARD  PENINSULA. 

CHARACTER  AND  DISTRIBUTION  OF  METAMORPHIC  ROCKS. 

The  schists  form  the  greater  part  of  the  metamorphic  complex  and 
may  be  described  according  to  the  mineral  or  minerals  characteristic 
of  them.  The  schists  most  commonly  found  are  quartzose,  graphitic 
or  carbonaceous,  biotitic,  feldspathic,  and  calcareous.  Gradations 
between  different  types  are  frequent  and  the  differentiation  is  by  no 
means  certain.  It  appears,  however,  that  the  present  lithologic  dif- 
ferences are  in  considerable  measure  due  to  original  characters,  so 
that  in  a broad  way  identity  of  lithology  may  be  taken  as  indicating 
deposits  formed  at  essentially  the  same  time.  This  is  generally  true 
of  the  graphitic  schists,  is  sometimes  true  of  the  calcareous  schists, 
and  is  seldom  true  of  the  biotite  schists. 

Owing  to  the  complexity  of  structure  and  the  insufficient  examina- 
tions of  parts  of  the  field,  it  has  not  been  possible  to  indicate  on  the 
map  consistently  the  areas  occupied  by  the  various  types  of  schist. 
It  has  been  found  necessary  to  show  areas  which,  for  want  of  a better 
name,  have  been  called  “ undifferentiated  metamorphic  rocks.”  These 
undoubtedly  contain  representatives  of  some  of  the  rocks  that  have 

“Maddren,  A.  G.,  Innoko  gold  placer  district,  Alaska:  Bull.  IT.  S.  Geol.  Survey  No.  410, 
1910,  p.  43. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


41 


been  differentiated  as  well  as  others,  but,  as  stated  above,  either  the 
scale  of  the  map  or  the  absence  of  definite  data  has  precluded  accurate 
mapping.  In  a measure  the  lumping  together  of  diverse  units  has 
obscured  geologic  relations,  and  on  the  map  it  frequently  happens 
that  the  undifferentiated  metamorphic  rock  symbol  terminates  some 
other  symbol  in  an  abnormal  manner.  As  a specific  instance  of  this 
kind  may  be  cited  the  region  for  10  miles  north  and  west  of  Bluff'. 
Detailed  traverses  along  the  western  margin  of  this  area  showed  the 
presence  of  the  feldspathic  schists  of  igneous  origin,  but  no  other 
data  are  available  south  of  Fox  Creek,  except  in  the  immediate 
vicinity  of  Bluff.  Therefore,  although  it  is  probable  that  much  of 
the  region  is  of  the  feldspathic  schist  type,  it  seems  unsafe  to  map 
the  distribution  in  this  100  or  more  square  miles  on  such  slight 
evidence.  Thus  at  the  risk  of  obscuring  the  important  fact  that  the 
feldspathic  schists  along  the  western  margin  of  the  map  are  continu- 
ous with  the  feldspathic  schists  of  the  Bluff  and  Fox  Creek  regions 
it  has  seemed  best  to  adopt  the  more  noncommittal  course  of  showing 
that  the  rocks  have  not  been  adequately  differentiated. 

As  shown  in  Plate  VI  there  are  five  main  areas  of  undifferentiated 
metamorphic  rocks — (1)  around  Kwik  River,  (2)  between  the  two 
lava  flows  north  of  the  Koyuk,  (3)  the  Bendeleben  Range  from  the 
head  of  Death  Valley  westward,  (4)  the  western  part  of  the  mapped 
area  south  of  the  Niukluk,  and  (5)  along  the  western  flanks  of  the 
Darby  Range  extending  southward  across  the  head  of  Kachauik 
River  to  the  coast  of  Norton  Bay  east  of  Bluff. 

KWIK  RIVER  AREA. 

The  schist  area  at  the  head  of  Kwik  River  shows  few  exposures  in 
place,  and  practically  nothing  was  learned  regarding  the  structure 
and  relationship  of  the  rocks  of  the  region  except  that  they  are 
quartzose  schists.  Toward  the  east  or  near  the  limestone  area  at  the 
head  of  Kemvood  and  Mukluktulik  creeks  the  schists  are  predojni- 
nantly  very  dark  and  somewhat  graphitic,  and  the  rocks  may  be  the 
equivalent  of  some  of  the  black  slates  and  quartzites  found  in  places 
intimately  connected  with  dark  limestones.  Farther  west,  however, 
the  similarity  to  the  carbonaceous  schists  is  not  so  marked,  and  it  is 
possible  that  one  of  the  other  types  of  schist  is  represented. 

This  schist  is  highly  quartzose  in  all  places,  contains  some  chlorite, 
practically  no  garnet  or  feldspar,  and  few  specimens  of  it  effervesce 
with  acid.  Numerous  cubical  cavities  show  that  it  contained  pyrite 
in  considerable  amounts.  It  finds  topographic  expression  in  a series 
of  massive,  slightly  dissected  hills  with  gentle  slopes  covered  with 
waste  and  devoid  of  outcrops.  Owing  to  the  absence  of  structural  de- 
terminations no  statement  can  be  made  of  the  thickness  or  relations  of 


42 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


the  member.  Looked  at  in  detail,  however,  the  minor  structures  show 
that  the  rocks  have  been  so  deformed  that  schistosity  has  been  pro- 
duced throughout.  On  the  flat-topped,  massive  hill  east  of  camp  C4 
the  float  shows  in  almost  all  instances  clearly  marked  evidence  of 
two  structures — that  is  to  say,  the  plication  of  a previously  developed 
cleavage  and  color  banding.  As  this  structure  was  not  seen  in  place, 
however,  the  relation  of  the  two  structures  in  age  could  not  be  deter- 
mined. The  only  fact  bearing  on  this  point  is  the  occurrence  of  a 
shattered  anticline  west  of  camp  C3,  the  axis  of  which  strikes  north- 
west-southeast and  pitches  strongly  to  the  northwest. 

AREA  NORTH  OF  THE  KOYUK. 

The  area  of  undifferentiated  metamorphic  rocks  north  of  the  Kovuk 
was  not  visited  by  the  party  of  1909.  From  the  manuscript  notes 
of  Moffit,  who  studied  the  region  in  1903,  it  is  evident  that  a number 
of  different  types  of  schist  were  found.  East  of  Iviwalik  Mountain 
black  slates  and  carbonaceous  schists  are  closely  associated  with  the 
limestone  area.  As  the  granite  contact  of  Kiwalik  Mountain  is  ap- 
proached biotite  forms  an  important  constituent,  although  it  is  of 
no  stratigraphic  significance,  as  it  is  undoubtedly  due  to  the  intrusion 
of  the  granite.  West  of  Kiwalik  Mountain  the  schists,  according  to 
Mendenhall’s  field  notes,  are  mainly  calcareous,  with  some  greenish 
schists  which  may  correspond  to  the  feldspathic  schists  to  be  de- 
scribed later.  Quartz-chlorite  schists  are  abundant  in  places,  but 
their  stratigraphic  position,  with  respect  to  the  others,  has  not  been 
determined. 

BENDELEBEN  MOUNTAIN  AREA. 

According  to  the  geologists  who  studied  contiguous  areas  in  1900, 
the  metamorphic  schists  of  the  Bendeleben  Mountains  were  considered 
distinct  from  the  other  schists  of  the  region  and  were  therefore  given  a 
name  and  assigned  to  a more  or  less  definite  stratigraphic  position. 
In  1908  the  senior  writer  of  this  report  made  a cross  section  of  the 
range  along  the  western  margin  of  the  area,  and  in  1909  the  party  had 
the  opportunity  of  studying  the  section  north  and  wyest  of  Death 
Valley,  where  rocks  previously  considered  as  belonging  to  the  Kig- 
luaik  group  are  exposed.  These  studies  have  caused  considerable 
doubt  as  to  the  desirability  of  retaining  the  stratigraphy  as  outlined 
formerly,  and  these  rocks  will  therefore  be  treated  as  “undifferentiated 
metamorphic  rocks.” 

Mendenhall a mapped  the  Bendeleben  Range  as  two  large  areas  of 
massive  intrusives,  mostly  granite,  vTith  a metamorphic  series  sep- 

“ Mendenhall,  W.  C.,  A reconnaissance  in  the  Norton  Bay  region,  Alaska,  in  1900,  a 
special  publication  of  the  U.  S.  Geol.  Survey,  1901. 


NORTON  BAY-NULATO  REGION,  ALASKA.  43 

arating  the  two.  In  the  text  the  following  statement a of  this  schist 
area  is  made: 

About  the  head  of  Fish  River  the  mountains  are  chiefly  granitic,  but  along 
their  flanks  and  sometimes  extending  through  them  in  belts  of  varying  breadth 
which  mark  the  passes  are  areas  of  schistose  sediments. 

About  a mile  above  the  camp  of  July  20  along  the  creek  is  an  outcrop  of 
a rusty  and  very  graphitic  schist  associated  with  more  calcareous  phases. 
Five  miles  farther  along  the  right  bank  of  this  same  branch  of  Fish  River 
is  an  outcrop  of  bluff  slates  with  very  little  calcareous  matter,  while  2 
miles  farther  northwest  in  a gap  between  two  branches  of  Fish  River  the 
series  is  represented  by  a white,  coarsely  crystalline  marble.  This  narrow  belt 
of  the  crystalline  series  between  two  great  intrusive  granitic  masses  expands 
to  the  northwest. 

Collier *  6 states  in  a report  published  in  1908,  the  field  work  for 
which  was  completed  in  1903 : 

The  only  section  across  the  Bendeleben  Range  which  has  been  examined  by 
the  writer  is  along  Parantulik  (Pargon)  River  and  Ella  Creek,  between  the 
heads  of  which  there  is  a low  pass.  The  structure  here  appears  to  be  anti- 
clinal and  the  prevailing  rocks  are  dark-colored  quartz-biotite  schists  and 
gneisses  similar  to  those  of  the  Kigluaik  Range.  Sills  and  dikes  of  coarse- 
grained granite  or  pegmatite  are  also  present.  White  crystalline  limestones 
containing  scattered  grains  of  graphite  occur  in  beds  20  feet  or  more  in  thick- 
ness interbedded  with  the  schists  along  Parantulik  River  from  a point  near  its 
head  to  the  edge  of  the  Fish  River  lowland. 

Smith  in  1908  studied  a section  along  the  upper  Niukluk  across  the 
range  to  the  northern  margin.  The  examination  showed  that  the 
section  was  composed  of  quartzose  schists,  a few  much  dislocated  lime- 
stones, a complex  and  very  numerous  series  of  granitic  intrusives, 
and  black  carbonaceous  slates  and  schists.  All  of  the  rocks  were 
highly  biotitic.  North  of  Birch  Creek  black  slates  and  calcareous 
schists  predominated.  All  the  rocks  were  much  sheared  and  original 
structures  were  not  discoverable,  but  the  diversity  of  trends  of  the 
cleavage  noted  were  such  as  to  lend  but  slight  support  to  the  idea 
that  the  structure  is  in  general  east  and  west. 

The  observations  of  the  party  in  1909  in  the  Bendeleben  Range 
were  confined  to  the  extreme  eastern  part  and  consisted  of  a study  of 
the  2,200-foot  hill  northwest  of  camp  C7,  and  of  the  3,000-foot  hill 
north  of  camp  C8.  On  the  first  traverse  were  found  biotitic  schists 
with  some  thin  limestone  members  and  greenstone  schists,  all  thor- 
oughly cut  up  by  granitic  intrusions  of  later  date.  On  the  second 
traverse  the  same  kinds  of  schists  were  also  found,  but  in  addition 
there  were  some  carbonaceous  schists  and  greenstones  were  more 
abundant. 

a Op.  cit.,  pp.  200-201. 

6 Collier,  A.  J.,  and  others,  The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska : 
Bull.  U.  S.  Geol.  Survey  No.  328,  1908,  pp.  67-68. 


44 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


Southwest  from  camp  C8  to  C9,  3 or  4 miles  from  camp  C8,  the 
schists  are  not  much  intruded  by  granites  and  belong  almost  entirely 
to  the  group  of  feldspathic  schists  with  here  and  there  a few  lime- 
stones and  a little  black  slate.  These  schists  appear  to  be  fully  as 
metamorphosed  as  those  to  the  north  and  strongly  suggest  a trend 
more  nearly  north  and  south  than  east  and  west. 

On  account,  however,  of  the  small  amount  of  investigation  in  the 
larger  part  of  the  Bendeleben  Mountains  it  seems  unsafe  to  differ- 
entiate the  schists  on  the  map.  They  are  characterized  as  a whole 
by  the  presence  of  biotite,  but  this  is  of  late  origin  and  is  not  strati- 
graphically  significant.  Otherwise  all  the  various  kinds  of  schists 
and  other  metamorphic  rocks  have  been  recognized,  and  the  series 
therefore  can  not  be  regarded  as  a unit. 

AREA  SOUTH  OF  THE  NIUKLUK. 

The  undifferentiated  metamorphic  rocks  along  the  western  margin 
of  the  mapped  area  south  of  the  Niukluk  have  been  studied  in 
detail  where  they  enter  the  Solomon  and  Casadepaga  quadrangles. 
From  this  study  it  was  determined  that  the  schists  were  mainly  of 
the  quartz  chlorite  type  and  that  they  underlay  the  limestone  near  the 
head  of  Fox  Creek.  North  of  the  Niukluk,  however,  younger  schists, 
called  in  the  region  to  the  west  the  Puckmummie  schist,0  consisting 
mainly  of  black  slates  and  thin  limestones,  probably  overlie  the  lime- 
stone. These  rocks  seem  to  merge  with  the  black  slates  that  form  the 
southern  flanks  of  Mount  Bendeleben  and  would  indicate  enormous 
deformation  not  recognizable  by  surface  features. 

West  of  the  belt  of  greenstone  schists  the  rocks  show  many  different 
lithologic  types,  but  black  quartzitic  schists,  quartz  chlorite  schists, 
and  calcareous  schists  predominate  in  such  complex  relations  that  no 
separation  of  them  has  been  made.  Undoubtedly  some  of  the 
quartzose  schists  correspond  to  the  older  schists  to  the  west,  but  some 
are  the  sheared  equivalents  of  the  heavy  limestones  and  others  may 
belong  to  the  black  slate  series,  which  will  be  described  later.  In 
the  southern  part  of  this  western  area  a large  part  of  the  undiffer- 
entiated metamorphic  series  is  the  equivalent  of  the  greenstone  and 
feldspathic  schist  series,  but  this  part  has  not  been  closely  examined. 

AREA  WEST  OF  THE  DARBY  RANGE. 

The  fifth  large  area  of  undifferentiated  metamorphic  rocks  is  along 
the  western  flank  of  the  Darby  Range  and  extends  southward  along 
the  head  of  Kachauik  Creek  to  the  coast  west  of  Rocky  Point.  In 
this  area  schists  of  a great  variety  of  lithologic  types  are  found  in 
such  intricate  interrelations  that  considerable  generalization  is  re- 

a Smith,  P.  S.,  Geology  and  mineral  resources  of  the  Solomon  and  Casadepaga  quad- 
rangles : Bull.  U.  S.  Geol.  Survey  No.  433,  1910,  pp.  62-66. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  VII 


Unconsolidated  deposits 

Sand,  gravel,  and  some  moraine 


GEOLOGIC  MAP  OF  OMILAK  REGION. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


45 


quired  in  mapping  them.  Plate  VII  shows  a part  of  this  region  south 
of  the  Omilak  mine  on  a scale  of  2 miles  to  the  inch  and  indicates 
the  geology  in  some  detail.  For  the  present  the  main  interest  in  this 
map  centers  in  the  arrangement  of  the  various  schist  and  limestone 
bands.  Even  on  this  larger  scale  map,  however,  it  is  impossible  to 
show  the  actual  complexity  of  the  geology.  Schists  of  many  differ- 
ent lithologic  characters  are  found  in  the  area  covered  by  this  map, 
but  practically  all  of  them  are  more  or  less  biotitic.  Some  car- 
bonaceous schists  and  quartzites  suggest  the  presence  of  younger 
members  of  the  schist  series,  whereas  the  relations  of  others  show 
that  they  are  older  than  the  limestones  which  are  believed  to  be 
higher  in  the  series. 

In  the  undifferentiated  schist  area  at  the  head  of  Kachauik  Creek 
the  schists  are  biotitic,  chloritic,  and  sometimes  calcareous,  and  dis- 
crimination of  the  various  types  is  impossible  with  the  poor  ex- 
posures. Southward,  however,  schists  lying  below  the  limestone  at 
White  Mountain  have  been  recognized  by  Mendenhall  and  Collier  on 
Fish  River.  Similar  schists  extend  southward  and  probably  form 
most  of  the  hills  in  the  low  divide  between  Norton  Sound  and  the 
Golofnin  Bay  drainage.  Unfortunately,  however,  this  area  has  not 
been  studied  in  detail  and  the  differentiation  of  the  rocks  must  await 
further  investigation. 

SUMMARY. 

The  undifferentiated  metamorphic  rocks  are  highly  sheared  and 
cleavage  is  the  dominant  structure  observed.  In  many  parts  of  the 
field  the  cleavage  is  at  a low  angle.  In  many  outcrops  where  an 
earlier  structure  is  recognizable  the  two  structures  do  not  coincide, 
and  it  is  believed  that  this  is  the  general  rule.  Faulting  is  also  com- 
mon in  the  schists,  but  the  amount  of  dislocation  is  generally  not 
determinable  on  account  of  the  absence  of  clearly  defined  horizon 
markers. 

In  the  typical  schist  areas  where  igneous  intrusions  have  not 
afforded  more  resistance  to  erosion,  the  topographic  forms  produced 
are  smooth  and  rolling.  Characteristic  schist  topography  is  dom- 
inant in  the  eastern  part  of  the  Kwik  River  Basin  and  is  typical  of 
a considerable  part  of  southeastern  Seward  Peninsula.  Here  and 
there  on  the  summits  of  the  ridges  rocky  knobs  of  irregular  form  rise 
10  to  30  feet  above  the  surrounding  uplands.  In  the  mountainous 
regions  the  schists  form  rugged  hills  with  steep  slopes.  As  a whole, 
however,  the  schists  are  less  resistant  to  erosion  than  the  limestone 
or  igneous  rocks  and  are  therefore  found  in  the  lower  land  and 
passes. 

Intrusive  activity  of  several  periods  has  affected  the  undifferenti- 
ated metamorphic  rocks.  Greenstones,  granites,  diorites,  and  other 


46 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


igneous  rocks  cut  these  schists  and  have  each  had  a share  in  the 
metamorphism  and  obliteration  of  the  original  characters  and  distri- 
bution of  the  schists. 

As  the  undifferentiated  schists  as  mapped  include  several  strati- 
graphic units  of  different  origin,  form,  and  age,  no  general  state- 
ment can  be  made  of  the  relation  of  these  rocks  to  the  others  of  the 
region.  It  is  clear,  however,  that  some  of  these  schists  are  older  than 
the  limestones  and  other  rocks  which  will  be  described  later,  for  they 
underlie  them.  The  question  of  age  and  relationship  will  be  dis- 
cussed more  fully  in  the  section  on  historical  geology.  For  the 
present,  however,  it  seems  justifiable  to  state  that,  taken  as  a whole, 
the  area  of  undifferentiated  metamorphic.  rocks  is  composed  of  rocks 
older  than  any  of  the  other  areas  indicated  on  the  map  and  is  chiefly 
pre-Silurian. 

PALEOZOIC  ROCKS. 

There  are  five  main  areas  of  rocks  which  are  presumably  of  Pale- 
ozoic age,  and,  although  more  detailed  investigation  will  undoubt- 
edly show  that  parts  of  the  undifferentiated  metamorphic  rocks  are 
of  similar  age,  the  lack  of  information  and  the  complexity  of  the 
structure  forbid  closer  correlation  at  this  time.  Characteristically 
all  the  known  Paleozoic  rocks  are  metamorphosed  and  lithologically 
consist  of  limestones  and  schists  complexly  folded  and  faulted.  As 
indicated  on  the  map  (PI.  VI),  these  five  areas  are  as  follows:  The 
ridges  east  of  the  Darby  range  extending  from  the  coast  of  Norton 
Sound  on  the  south  to  beyond  the  Koyuk  on  the  north ; the  hills  east 
and  west  of  the  Fish  River  gorge  from  the  head  of  Kachauik  Creek 
to  Ophir  Creek,  including  the  limestone  hills  on  Fish  River  near  White 
Mountain;  the  region  south  and  east  of  the  Omilak  mine;  the  area 
exposed  on  the  seacoast  from  Bluff  to  Topkok  Head  extending  inland 
an  undetermined  distance ; and  the  hills  at  the  head  of  the  Mukluk- 
tulik.  In  addition  to  these  larger  areas  there  are  smaller  areas,  some 
shown  on  the  map  and  others  included  in  the  undifferentiated  meta- 
morphic rocks. 

AREA  EAST  OF  THE  DARBY  RANGE. 

Along  the  eastern  flank  of  the  Darby  Range  a group  of  rocks, 
consisting  mainly  of  limestones  with  some  schistose  bands  and  closely 
associated  with  black  slates  and  quartzites,  was  noted  b}^  Mendenhall 
in  1900,  and  studied  in  some  detail  by  the  survey  party  in  1909. 
This  belt  extends  from  the  seacoast  with  a general  northerly  trend 
across  Kwiniuk  River  and  along  the  Tubutulik,  forms  the  eastern 
divide  of  Death  Valley,  and  is  exposed  north  of  the  Koyuk  in  the 
hills  east  of  Kiwalik  Mountain.  Although  it  probably  extends  still 
farther  north,  its  obvious  continuation  ceases  at  this  place.  In  this 
distance  the  average  width  of  the  belt  is  from  4 to  6 miles.  Capital 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  VIM 


B. 

PALEOZOIC  LIMESTONE,  DARBY  PENINSULA. 
A,  Intruded  by  greenstone;  B,  Intruded  by  granite. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


47 


exposures  are  afforded  along  the  seacoast  from  the  mouth  of  the 
Miniatulik  southeast  nearly  to  Carson  Creek.  Studied  in  detail,  the 
exposures  show  a great  thickness  of  limestones,  considerable  dolo- 
mite, black  carbonaceous  slates,  and  schists,  all  cut  by  greenstones, 
granites,  and  diorites. 

The  limestones  are  in  places  grayish  blue  but  in  other  places 
nearly  black.  Associated  with  them  in  such  intimate  and  complex 
relations  that  they  can  be  separated  only  by  refined  investigation  are 
dolomites  usually  of  a light-gray,  slightly  pinkish  color.  Light- 
colored  dolomites  have  been  recognized  in  the  sea  cliff  exposures,  in 
the  hills  between  the  Kwiniuk  and  the  Miniatulik  east  of  camp  C15, 
and  in  the  hills  near  camp  C5,  and  east  of  Death  Valley.  No  meas- 
urement of  the  thickness  has  been  made,  but  it  seems  certain  that  not 
less  than  1,000  feet  are  required  to  account  for  the  field  distribution. 

Although  highly  metamorphosed,  poorly  preserved  fossils  were 
found  in  the  light-colored  dolomite  2^  miles  east  of  camp  C15  on 
Kwiniuk  River.  According  to  Kindle,  who  examined  the  collection — 

Lot  9AS130,  locality  9AS180,  Kwiniuk  divide,  is  represented  by  a single 
specimen.  This  is  the  now  well-known  though  undescribed  thick-shelled  lamelli- 
branch  which  has  generally  been  compared  with  Megalomus  canadensis.  This 
fossil  indicates  a late  Silurian  age  for  the  bed  from  which  it  comes.  It  is 
interesting  to  note  that  it  occurs  here  as  at  White  Mountain  (and  at  the 
Ramparts  of  the  Yukon)  in  a highly  magnesian  limestone.  • The  indexical 
value  of  this  fossil  rests  upon  our  knowledge  of  its  faunal  associations  in 
southeast  Alaska,  where  it  occurs  in  association  with  various  late  Silurian 
fossils. 

At  this  place  the  areal  relations  are  indeterminate.  There  is  some 
very  dark-colored  limestone  which  seems  to  be  either,  a thin  band 
between  two  dolomitic  bands  or  else  unconformably  overlies  the 
dolomite.  Northward,  however,  near  camp  C5,  at  the  head -of  Lost 
Creek,  the  dolomite  lies  to  the  east;  that  is,  apparently  on  top  of 
the  dark  limestone.  This  may  be  due  to  intense  folding  or  faulting, 
or  it  may  be  normal  depositional  sequence. 

The  limestones  associated  with  the  Silurian  dolomite  range  in 
color  from  light  bluish  gray,  nearly  white,  to  dark  gray,’  almost 
black.  They  are  exposed  at  a number  of  places  in  the  mapped  belt, 
but  the  most  significant  outcrops  are  those  found  in  the  divide  be- 
tween the  Kwiniuk  and  the  Tubutulik  and  along  the  coast  from 
camp  C16  to  camp  C19.  In  all  places  the  limestone  is  folded  and  con- 
torted with  many  faults  and  with  calcite  and  some  quartz  veins.  It 
has  been  intruded  by  greenstones,  granites,  and  diorites.  Plate  VIII, 
A and  B , show  exposures  of  these  limestones  in  the  neighborhood  of 
the  intrusions  and  afford  a fairly  good  idea  of  the  general  charac- 
ters. Plate  VIII,  A , especially  shows  the  well-marked  bedding 
of  the  limestone,  emphasized  by  the  alternation  of  bands  of  light  and 
dark  colored  limestone.  Plate  VIII,  B , shows  a more  schistose  phase, 


48 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


with  the  bedding  marked  by  the  color  banding  particularly  evident 
in  the  right-hand  portion. 

At  many  places  along  the  sea  cliffs  poorly  preserved  fossils  were 
found,  and,  although  none  of  them  was  sufficiently  perfect  or  distinct 
to  permit  specific  determination,  there  seems  to  be  no  question  that 
they  represent  a higher  horizon  than  that  of  the  dplomite  already 
described.  According  to  Kindle,  who  examined  the  collections,  a 
Devonian  or  Carboniferous  horizon  is  represented,  and  in  his  opinion 
the  higher  rather  than  the  lower  portion  is  more  probable.  Ulrich, 
who  examined  the  fossils  hastily,  also  agreed  with  the  probable 
Devonian  or  Carboniferous  determination,  but  appeared  to  think  the 
lower  rather  than  the  higher  position  was  the  more  probable.  There 
does  not  seem,  however,  to  have  been  any  marked  difference  between 
the  amount  of  metamorphism  or  deformation  undergone  by  the 
Silurian  and  the  Devonian-Carboniferous  rocks. 

In  the  limestone  hills  south  of  the  Kwiniuk  River  conditions  simi- 
lar to  those  noted  on  the  coast  were  observed,  and  it  is  evident  that 
the  same  group  of  rocks  is  represented.  The  higher  hills  are  usually 
formed  of  limestone,  but  the  saddles  are  here  and  there  formed  of 
feldspathic  schists  presumably  of  later  origin.  Owing  to  the  scale 
of  the  map  it  has  not  been  practicable  to  indicate  these  later  schists 
except  in  a most  general  way,  but  it  should  be  stated  that  these  schists 
and  greenstones  are  principally  of  igneous  origin;  they  are  not  in- 
cluded in  this  group  of  sedimentary  rocks,  but  will  be  described  later 
under  the  igneous  rocks.  . 

In  the  region  between  the  coast  and  Kwiniuk  River  there  are,  how- 
ever, slates  and  schists  of  sedimentary  origin  which  at  the  present 
time  are  not  to  be  separated  from  the  Paleozoic  limestones  already 
described.  The  precise  relation  has  not  been  satisfactorily  deter- 
mined and  fossils  have  not  been  found  in  them.  There  is  small  reason, 
however,  to  doubt  that  they  are  closely  related  to  the  Devonian-Car- 
boniferous group. 

These  schists  and  quartzitic  slates  are  perhaps  most  extensively 
exposed  in  the  upper  part  of  Mount  Kwiniuk,  but  their  structure 
and  other  characters  are  most  clearly  seen  in  the  coast  section.  Usu- 
ally these  rocks  are  of  a black  color  due  to  the  presence  of  finely 
divided  carbonaceous  matter  which,  in  some  places  at  least,  is  graphite. 
The  rocks  are  very  quartzose  and  are  low  in  other  minerals.  Cleav- 
age is  commonly  developed,  but  schistosity  is  not  so  pronounced  as 
in  the  older  schists.  Apparently  schistosity  is  more  common  in  the  less 
quartzose  parts  of  the  rock.  In  the  normal  quartzose  phases  the  rock 
has  fractured  and  has  had  jointing  developed,  which  causes  the  rock 
to  disintegrate  into  a talus  of  small  rectangular  blocks.  No  measure- 
ments of  the  thickness  of  the  slate-schist  member  were  obtained,  but 
it  must  be  at  least  several  hundred  feet. 


NORTON  BAY-NULATO  REGION,  ALASKA.  49 

From  the  foregoing  description,  it  is  evident  that  a large  mass 
of  Paleozoic  sediments  which  have  undergone  more  or  less  fully  the 
same  general  history  lies  east  of  the  Darby  Range.  These  rocks,  which 
are  complexly  folded,  faulted,  and  metamorphosed,  consist  mainly 
of  dark-colored  limestones  with  subordinate  thicknesses  of  dolo- 
mite, black  slates,  and  schists.  They  are  cut  by  intrusives  of  green- 
stone, granite,  and  diorite  and  in  age  include  members  ranging  from 
Silurian  to  Devonian  or  Carboniferous,  with  neither  the  overlying 
nor  the  underlying  rocks  exposed  in  close  relationship.  They  have 
a thickness  of  at  least  2,500  feet  and,  if  considerable  reduplication 
has  not  occurred,  their  thickness  possibly  exceeds  this  amount  many 
times.  They  form  bold  prominent  hills  with  scanty  vegetation,  cov- 
ered with  an  angular  frost-riven  talus  of  float,  and  are  widely  devel- 
oped throughout  Seward  Peninsula. 

FISH  RIVER  AREA  WEST  OF  KACHAUIK  CREEK  TO  OPHIR  CREEK. 

In  the  hills  east  and  west  of  the  Fish  River  gorge  from  the  head 
of  Kachauik  Creek  to  Ophir  Creek,  including  the  limestone  hills  on 
Fish  River  near  White  Mountain,  is  an  area  of  Paleozoic  rocks  to 
be  correlated  with  the  rocks  of  the  Kwiniuk  region.  The  most 
definite  data  regarding  the  geology  of  this  field  are  afforded  by  the 
exposures  near  White  Mountain.  Fossiliferous  beds  were  found  here 
by  Mendenhall  in  1900  and  have  been  further  studied  by  Collier, 
Hess,  Kindle,  and  Smith,  but  were  not  visited  by  the  party  in  1909. 
In  the  description  of  the  exposures  on  the  lower  Fish  River  it  will 
not  be  possible  except  at  great  sacrifice  of  brevity  to  credit  the  par- 
ticular contributions  of  each  of  the  different  geologists,  but  it  may 
be  remarked  that  the  present  writers  are  acting  more  in  the  role  of 
compilers  than  contributors. 

Three  miles  southeast  of  White  Mountain  micaceous,  highly  met- 
amorphic  schists  dipping  north  underlie,  probably  unconformably, 
the  rocks  farther  up  the  river.  There  is  a considerable  area  of  river 
flood  plain  in  which  exposures  are  lacking,  and  then  come  white 
dolomite  hills  from  which  the  settlement  of  White  Mountain  is 
named.  The  dolomite  is  lithologically  identical  with  the  dolomite 
of  the  Kwiniuk  region,  and  furthermore  contains  the  same  thick- 
shelled  lamellibranch  ( Megolomus  canadensis)  together  with  cer- 
tain other  Silurian  forms ; the  correlation  seems  therefore  well 
founded.  Less  schistosity  has  been  developed  in  the  dolomite  than 
in  the  rocks  to  the  southeast,  and  for  that  reason  there  is  believed 
to  be  an  unconformity  between  the  two. 

Farther  upstream  and — if  the  apparent  structure  of  the  rocks  is 
the  true  structure — overlying  the  dolomite  is  a series  of  schists. 
Considerable  doubt  is  felt  as  to  the  relation  of  these  schists,  and  it 
71469°— Bull.  449— II 4 


50 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


has  been  deemed  expedient  in  this  report  to  place  them  among  the 
undifferentiated  schists  rather  than  to  express  their  possible  correla- 
tion with  the  Paleozoic  black  slate  of  the  Kwiniuk  region,  though  the 
latter  is  by  no  means  impossible.  Still  farther  upstream  near  the 
point  where  Fish  River  makes  an  east-west  bend  south  of  Steam- 
boat Slough  fossil  corals  have  been  found  in  a nearly  black  lime- 
stone. This  limestone  is  lithologically  identical  with  the  black  lime- 
stone of  the  Kwiniuk  locality,  and  the  fossils  have  been  determined 
to  be  analogous.  As  a whole  the  rocks  on  lower  Fish  River  are  less 
metamorphosed  than  in  the  Kwiniuk  region.  Near  the  black  De- 
vonian or  Carboniferous  limestone  are  black  graphitic  slates  the 
relation  of  which  is  not  determinable,  but  they  seem  to  be  litho- 
logically similar  to  the  slates  on  Mount  Kwiniuk  in  the  more  eastern 
locality. 

Along  the  divide  between  the  Fish  River  lowland  and  Golofnin 
Sound  from  camp  C23  west  to  the  head  of  Mystery  Creek  limestones 
with  black  slates  form  the  country  rock.  None  of  the  beds,  how- 
ever, were  recognized  as  dolomitic.  As  a whole  the  rocks  from 
camp  C23  to  Fish  River  are  more  schistose  than  their  equivalents  at 
White  and  at  Black  mountains,  but  the  dominant  north-south  trend 
seems  to  be  strong  reason  for  connecting  the  rocks  at  the  two  places. 
Apparently,  the  dip  of  these  beds  east  of  Fish  River  is  to  the  west 
at  rather  high  angles,  but  original  bedding  is  seldom  recognizable, 
and  the  occurrence  of  diverse  dip  at  places  where  the  two  structures 
have  been  determined  points  strongly  to  the  conclusion  that  the 
great  thickness  represented  by  the  surface  exposures  is  due  to  re- 
duplication through  folding. 

West  of  Fish  River  gorge  the  schistose  character  of  the  lime- 
stones is  less  pronounced,  the  rock  becomes  more  massive  and,  al- 
though shattered  and  deformed,  shows  not  much  cleavage  and  but  few 
secondary  minerals.  Immediately  beneath  the  limestone  at  the  head 
of  Mystery  Creek  lies  a considerable  thickness  of  black  quartzitic  and 
graphitic  slates.  These  have  not  been  adequately  differentiated  in 
the  field,  and  it  is  probable  that  part  of  the  undifferentiated  schists 
on  Melsing  Creek  may  belong  to  the  same  schist  series  as  those  in  the 
Kwiniuk  region,  for  black  graphitic  slates  closely  associated  with 
limestones  are  known  to  occur  at  many  places  in  the  basin  of  this 
stream. 

Whether  the  Paleozoic  rocks  extend  northward  across  the  Fish 
River  flats  and  are  represented  by  the  limestone-slate  group  at  the 
head  of  Fish  River  and  Boston  Creek  has  not  been  definitely  proved! 
It  is  assumed,  however,  in  the  absence  of  conflicting  evidence,  that 
the  two  areas  are  the  same,  and  it  is  on  this  basis  that  they  have  been 
represented  by  the  same  pattern  on  the  geologic  map  (PI.  VI). 
According  to  Mendenhall’s  field  notes  the  eastern  part  of  this  area 


BULLETIN  449  PLATE 


WESTERN  FLANKS  OF  DARBY  RANGE. 


NORTON"  BAY-NULATO  REGION,  ALASKA. 


51 


consists  mainly  of  white  crystalline  limestone  associated  with  gra- 
phitic and  rusty  schists.  So  far  as  his  records  show,  the  predomi- 
nant dip  is  to  the  west  and  the  strike  northwest. 

In  1909  F.  F.  Henshaw  traversed  the  lower  slopes  of  the  hills 
north  of  the  Fish  River  lowland  from  Pargon  River  as  far  east 
as  Boston  Creek  and  the  geology  for  that  part  of  the  range  is  repre- 
sented according  to  his  observations  and  is  only  approximate. 
Whether  this  belt  of  limestones  may  not  continue  still  farther  north 
across  the  range  is  not  known  because  of  the  absence  of  any  field 
investigation.  Although  such  an  interpretation  is  probable,  it  has 
been  deemed  expedient  to  truncate  abnormally  the  Paleozoic  pattern 
by  representing  the  northern  part  of  the  range  as  formed  of  undiffer- 
entiated rocks. 

In  the  vicinity  of  the  mountains  the  Paleozoic  rocks  are  cut  by 
granite  dikes  and  are  locally  as  well  as  dynamically  metamorphosed. 
South  of  the  Fish  River  lowland  the  Paleozoic  rocks  are  also  cut  by 
granites  and  in  addition  are  intruded  by  greenstones.  The  latter 
undoubtedly  would  be  found  in  the  northern  area  also  if  more  of  the 
region  had  been  examined.  It  should  be  noted  that  where  mica-like 
minerals  occur  in  the  Paleozoic  rocks  near  the  granitic  intrusives  the 
mineral  is  usually  biotite,  whereas  in  the  parts  remote  from  the  in- 
fluence of  the  granite  the  mineral  is  chlorite,  and  biotite  is  absent. 

OMILAK  MINE  AREA  ON  WEST  SLOPES  OF  DARBY  RANGE. 

East  of  the  area  of  Paleozoic  rocks  just  described  there  are  lime- 
stones which  resemble  in  many  features  those  of  the  Kwiniuk  region, 
and  although  the  correlation  is  by  no  means  conclusive,  it  is  the  closest 
that  can  be  made  with  the  data  now  available.  No  fossils  have  been 
found  in  these  rocks  and  their  structure  is  so  complex  that  any  relation 
between  the  various  units  may  be  postulated.  The  correlation  be- 
tween the  limestones  east  and  south  of  the  Omilak  mine  has  been 
based  almost  entirely  on  lithologic  evidence.  The  geologic  map  of 
the  Omilak  region  (PL  VII,  p.  45)  shows  the  distribution  of  the 
rocks  in  greater  detail  than  the  general  geologic  map  (PI.  VI). 
Even  this  scale,  however,  fails  to  express  the  complex  character  of 
structure  and  areal  distribution  of  the  rocks.  Plate  IX,  B , shows  a 
view  northward  from  a point  on  the  divide  between  the  two  branches 
of  the  Rathlatulik  about  3 miles  east  of  camp  C 11.  The  white  areas 
in  the  view  are  limestones  and  the  darker  parts  are  schist.  Some  of 
the  schists  are  undoubtedly  derived  from  rocks  of  igneous  origin,  but 
others  were  unquestionably  deposited  as  sediments.  Most  of  the 
limestones  are  ordinary  calcareous  rocks,  but  some  are  dolomitic.  In 
the  view  above  referred  to  at  several  places  in  the  eastern  or  right- 
hand  belt  of  white  rocks  light-colored  dolomites  have  been  found.  This 


52 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


fact  points  strongly  to  the  conclusion  that  these  beds  represent  the 
dolomitic  portion  of  the  Paleozoic  rocks  of  the  Kwiniuk  region. 

With  these  limestones  black  graphitic  quartzites  have  been  found 
here  and  there  similar  to  those  on  Mount  Kwiniuk.  This  type  of 
rock  is  not  so  abundant  as  at  the  other  places.  Its  apparently  small 
extent  is  believed  to  be  due  in  part  to  the  greater  amount  of  defor- 
mation and  contact  metamorphism  whereby  it  has  been  transformed 
into  a biotite  schist  or  into  a nearly  white  quartzite. 

BLUFF- TOPKOK  HEAD  AREA. 

The  westernmost  mapped  area  of  rocks  correlated  with  the  Paleo- 
zoic rocks  of  the  Kwiniuk  region  occur  near  Bluff  and  appear  at 
several  points  along  the  western  border  of  the  area.  Unfortunately, 
this  part  of  the  field  has  not  been  thoroughly  surveyed,  and  consider- 
able areas  which,  if  more  fully  known,  might  belong  to  this  series 
have  been  placed  in  the  undifferentiated  metamorphic  rocks. 

The  Bluff  region  was  not  visited  in  1909  and  the  account  here  given 
is  taken  from  a summary  report  by  Brooks  a in  1906. 

Richardson,  who  through  his  acquaintance  with  adjacent  areas  had  a broader 
knowledge  of  the  Bluff  region  than  the  writer,  divided  the  bedrock  terranes 
into  three  groups — (1)  a massive  gray  crystalline  limestone,  (2)  a mica  schist 
with  some  interbedded  graphitic  limestone,  and  (3)  a formation  of  massive 
limestones  and  mica  schist.  The  writer’s  observations  hardly  bear  out  the  cor- 
rectness of  this  succession  of  beds,  for  it  appears  to  him  that  there  is  only  one 
massive  white  limestone  which  is  succeeded  by  a mica  schist  and  graphitic  lime- 
stone formation.  Some  facts  are  presented  below  which  would  indicate  that  the 
mica  schists  are,  in  part  at  least,  altered  intrusives  and  hence  do  not  mark  any 
definite  stratigraphic  position. 

The  larger  structures  of  the  Bluff  region  appear  to  be  simple,  but  there  are 
many  minor  complications.  The  heavy  limestone  has  been  uplifted  into  a low 
dome,  whose  longer  axis  stretches  approximately  N.  70°  E.  About  3 miles  north- 
east of  Bluff  this  structure  carries  a limestone  underneath  the  younger  mica 
schists. 

It  is  evident  from  this  description  that  lithologically  the  same  rocks 
are  represented  here  as  in  the  Kwiniuk  region,  namely,  limestones, 
some  of  which  are  dark-colored,  suggesting  the  Devonian-Carbonif- 
erous limestone  and  black  graphitic  slates.  The  fact  that  these  rocks 
are  cut  by  intrusives  of  greenstone  is  also  indicative  of  a similarity 
between  the  two  regions.  Although  Brooks  correlated  these  rocks 
with  the  Port  Clarence  limestone,  the  fact  that  Devonian-Carbonif- 
erous rocks,  as  well  as  Silurian  and  possibly  older  ones,  may  be  rep- 
resented makes  it  undesirable  to  continue  that  correlation,  and  these 
rocks  are  therefore  mapped  as  Paleozoic. 

« Collier  and  others,  The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska  : Bull.  U.  S. 
Geol.  Survey  No.  328,  1908— The  Bluff  region,  pp.  285-286. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


53 


AREA  AT  THE  HEAD  OF  THE  MUKLUKTULIK. 

The  fifth  and  last  large  area  represented  on  the  southeastern  Sew- 
ard Peninsula  map  as  belonging  to  the  Paleozoic  rocks  is  the  eastern 
area  in  the  Mukluktulik  divide.  This  belt  trends  north  and  south. 
On  the  south  it  forms  Bald  Head  or  Isaacs  Point  where  it  is  cut  off 
by  the  sea.  To  the  north  a prominent  hill  locally  called  Haystack 
Mountain,  on  the  north  side  of  the  Koyuk  Valley,  marks  the  farthest 
extent  in  that  direction ; beyond  that  point  more  recent  igneous  rocks 
have  cut  or  covered  the  formation. 

At  the  eastern  margin  of  the  area  is  a belt  of  white  quartzite  a mile 
or  so  in  width.  This  is  cut  off  by  basic  lavas  that  form  the  hills 
east  of  Alameda  Creek.  It  is  believed  that  the  quartzite  is  equivalent 
to  the  black  quartzitic  and  graphitic  slates  of  Mount  Kwiniuk,  so 
metamorphosed  locally  by  the  igneous  rocks  that  the  carbon  has  been 
destroyed.  West  of  the  quartzite  ridge  there  is  a considerable  thick- 
ness of  calcareous  schist  with  some  white  limestone  bands,  but  on  the 
divide  at  the  head  of  Coal  Creek  a white,  completely  recrystallized 
limestone  forms  knobs  trending  a little  east  of  north.  Sink  holes  500 
to  600  feet  above  the  sea  are  common,  and  some  of  them  show  ledges 
of  limestone.  This  limestone  has  a strong  fetid  odor  when  freshly 
broken,  and  shows  no  original  bedding  or  signs  of  organic  remains. 
Farther  west,  about  7 miles  from  camp  B17,  at  the  mouth  of  the 
Koyuk,  alternations  of  black  graphitic  quartzitic  slates  or  schists  and 
limestone  beds  form  an  intricate  complex  about  2J  miles  wide  trend- 
ing northeast.  The  dips,  so  far  as  observed,  were  all  to  the  east,  but 
the  arrangement  of  the  different  lithologic  units  is  such  as  to  suggest 
extensive  faulting  or  overturned  and  crumpled  folds. 

Northwest  of  this  belt  of  alternations  of  black  slates  and  limestones 
for  4 miles  is  a series  of  dark  limestones  and  calcareous  schists  dip- 
ping southeast  and  striking  northeast-southwest.  Exposures  in  this 
field  are  rare  and  unsatisfactory.  The  western  part  of  this  area  is 
formed  of  a belt  2 miles  wide  of  black  carbonaceous  slates  and  schists. 
No  outcrops  in  place  were  observed,  but  the  unmixed  character  of 
the  float  points  to  the  conclusion  that  this  is  the  country  rock.  It  is 
in  all  essentials  lithologically  identical  with  the  slates  in  the  belt 
farther  east  already  described,  and  slight  hesitation  is  felt  in  ascrib- 
ing it  to  the  same  series.  More  detailed  work  would  undoubtedly 
permit  further  differentiation  of  these  two  distinct  lithologic  phases. 
For  the  present  it  may  be  stated  that  whereas  if,  on  the  one  hand, 
the  dip  is  considered  to  be  dominantly  to  the  east  the  section  shows 
a black  slate  and  quartzite  at  the  base,  succeeded  by  a thick  limestone 
and  limestone-schist  member,  succeeded  by  an  alternating  series  of 
limestones  and  black  slates,  succeeded  by  another  thick  series  of  lime- 
stones with  some  schistose  phases,  and  this  in  turn  followed  by  a mas- 


54 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


sive  quartzitic  horizon.  On  the  other  hand,  there  are  strong  reasons 
for  believing  that  reduplication  through  faulting  and  folding  may 
occur,  hence  there  may  be  only  one  limestone  and  one  black  slate 
member.  No  dolomite  was  observed  in  this  section. 

Mendenhall,  who  saw  the  section  of  these  rocks  near  Bald  Head, 
says : a 

Along  the  west  side  of  Bald  Head  gray  and  white  marbles  occur  infolded 
with  thin-bedded  limestones  and  schists,  and  blocks  of  these  rocks  cover  the 
beach.  The  point  of  the  promontory  is  a mass  of  heavy  black  graphitic  beds, 
and  the  eastern  face  exhibits  a slaty  and  schistose  phase,  the  rocks  being 
generally  dark.  Dip  and  strikes  are  variable  and  the  relations  are  obscure,  but 
evidently  complex. 

SUMMARY. 

From  the  foregoing  description  it  is  evident  that  there  is  a group 
of  limestones,  dolomites,  and  quartzose  graphitic  schists  which,  from 
the  few  fossils  found,  is  known  to  include  Silurian  and  Devonian- 
Carboniferous  horizons.  These  rocks  are  on  the  whole  less  metamor- 
phosed than  certain  quartz-chlorite  schists  on  which  they  are  sup- 
posed to  rest.  In  general,  the  trend  of  the  formation  is  north-south, 
with  complex  folding  and  faulting.  No  signs  of  a conglomerate  were 
noted  in  any  part  of  the  section,  and  it  is  presumed  that  the  Paleozoic 
rocks  were  laid  down  at  some  distance  from  the  shore  line.  This 
conclusion  is  further  suggested  by  the  wide  distribution  of  litholog- 
ically identical  rocks  over  the  southeastern  part  of  Seward  Peninsula 
where  the  metamorphic  rocks  outcrop.  Further  investigation  might 
lead  to  a more  precise  differentiation  of  the  various  lithologic  units, 
but  such  subdivision  would  probably  not  add  greatly  to  the  under- 
standing of  the  economic  problems  connected  with  this  group  of 
rocks. 

CRETACEOUS  SEDIMENTARY  ROCKS. 

In  the  eastern  part  of  the  Nulato-Council  region  a large  area,  ex- 
tending from  Norton  Bay  and  Koyuk  River  on  the  west  to  beyond 
the  Yukon  on  the  east,  is  occupied  by  a series  of  sedimentary  rocks, 
including  conglomerates,  grits,  sandstones,  shales,  and  thin  lignite 
beds.  These  deposits  extend  north  and  south  beyond  the  field  in- 
vestigated. The  only  other  rocks  within  this  area  are  a few  dikes 
near  Bonanza  Creek,  the  intrusive  massif  of  Christmas  Mountain, 
and  relatively  small  areas  of  Tertiary  effusives  on  the  Koyuk  and 
near  the  mouth  of  the  Koyukuk. 

Beds  similar  to  certain  of  those  found  in  the  main  sedimentary 
area  are  exposed  at  the  mouth  of  Koyuk  River  and  on  its  north 
bank  at  a point  about  4 miles  west  of  the  mouth  of  East  Fork,  also 

° Mendenhall,  W.  C.,  A reconnaissance  in  the  Norton  Bay  region,  Alaska,  in  1900, 
a special  publication  of  the  U.  S.  Geol.  Survey,  1901,  p.  202. 


NORTON  BAY-NULATO  REGION,  ALASKA.  55 

in  the  long  ridge  which  forms  the  Kwik-Tubutulik  divide.  These 
outlying  areas  of  sedimentary  rocks  comprise  only  a few  square 
miles. 

The  unmetamorphosed,  consolidated  sedimentary  rocks  of  the 
region  apparently  comprise  a single  conformable  series  of  great 
thickness.  Two  distinct  types  of  deposits  are  recognized  and  will 
be  described  in  their  order  of  occurrence  as  follows:  First,  a basal 
conglomerate  called  in  this  report  the  Ungalik  conglomerate ; second, 
an  overlying  group  of  sandstones  and  shales  called  the  Shaktolik 
group.  The  Shaktolik  group  is  separated  into  two  divisions,  the 
lower  distinguished  by  a preponderance  of  sandstones  over  shale,  and 
the  upper  in  which  shales  are  in  excess. 

UNGALIK  CONGLOMERATE. 

The  lowest  member  of  the  Cretaceous  sedimentary  series,  a basal 
conglomerate  of  marine  origin,  is  called  the  Ungalik  conglomerate, 
after  the  river  of  that  name,  along  whose  lower  course  it  was  first 
noted.  This  -formation  occurs  along  East  Fork  of  the  Koyuk  River 
and  on  the  Kwik-Tubutulik  divide.  (See  PL  V,  in  pocket.) 

The  Ungalik  conglomerate  is  exposed  in  steep-faced  cliffs  along 
Ungalik  River  and  forms  most  of  the  prominent  range  of  hills  be- 
tween the  river  and  the  coastal  plain  from  Bonanza  Creek  north  to 
a point  about  a mile  below  camp  AIT.  Here  the  strike  changes  and 
the  conglomerate  appears  in  the  hills  east  of  the  river.  Its  eastern 
limit  was  not  determined,  but  its  characteristic  pinnacled  topography 
does  not  extend  far  beyond  this  point. 

In  this  locality  the  conglomerate  ranges  in  texture  within  moderate 
limits,  the  coarsest  phases  carrying  bowlders  up  to  3 feet  in  diameter. 
Assortment  and  bedding  are  poor.  The  most  characteristic  ma- 
terials are  a variety  of  porphyritic  rocks  and  abundant  angular  feld- 
spar crystals  in  the  sandy  matrix.  A strong  red  coloration  on 
weathering  indicates  an  abundance  of  iron.  The  bedding  is  so  in- 
definite and  obscure  that  no  conclusive  evidence  as  to  the  attitude 
or  thickness  of  the  formation  could  be  obtained.  However,  a thick- 
ness of  at  least  several  hundred  feet  is  certain. 

That  deformation  has  been  intense  is  indicated  by  the  abundant 
slickensides  developed  both  in  the  conglomerate  and  at  its  contact 
with  other  members.  On  the  Ungalik  east  of  camp  A16  it  is  faulted 
against  black  slates  which  represent  a much  higher  horizon  in  the 
series.  At  this  point  the  slates  are  approximately  vertical.  In  the 
bluff  on  the  Ungalik  south  of  camp  A16  are  several  dikes  intruded 
in  the  conglomerate.  They  are  much  faulted  and  indicate  the 
amount  of  deformation  which  has  occured  throughout  the  vicinity. 
The  conglomerate  area  is  characterized  by  a rather  rugged  topog- 


56 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


raphy.  Where  there  is  considerable  relief  the  hilltops  and  sharp 
ridges  are  often  marked  by  bare,  rugged  pinnacles. 

The  conglomerate  is  the  basal  formation  of  the  sedimentary  series. 
It  is  made  up  of  rounded  debris  derived  from  the  older  formations, 
on  which  it  rests  unconformably.  It  chronicles  a period  of  more  or 
less  gradual  advancement  of  shore  conditions. 

On  East  Fork  the  conglomerate  occupies  a belt  about  8 miles  wide, 
trending  north  and  south.  It  is  similar  to  that  in  the  Ungalik 
Valley  in  texture  and  in  the  lack  of  assortment  and  bedding.  The 
materials  include  a variety  of  igneous  rock  types  in  the  outcrops 
near  camp  Bll.  Farther  wTest,  near  camp  B12,  it  consists  of  a 
variety  of  granitic  rocks  of  local  derivation.  Xo  conclusive  evidence 
as  to  the  attitude  or  thickness  of  the  conglomerate  in  the  East  Fork 
region  was  available,  but  the  relief  developed  in  the  formation  indi- 
cates a thickness  of  at  least  several  hundred  feet. 

Along  the  Kwik-Tubutulik  divide  the  IJngalik  conglomerate  belt 
has  a width  of  from  3 to  5 miles.  The  main  ridge  forming  this 
divide  and  its  northward  extension  into  the  Koyuk  drainage  basin  is 
composed  almost  entirely  of  limestone.  The  bowlders  are  smaller 
as  a rule  than  those  in  the  Ungalik  and  the  East  Fork  looalities. 
There  is  also  greater  variation  in  texture,  the  deposits  including 
grits  and  limy  sandstone  layers.  Some  of  the  latter  furnished  fossil 
plants  of  Cretaceous  age.  Fossil  corals  taken  from  a limestone 
bowlder  in  the  conglomerate  on  the  Kwik-Tubutulik  divide  about 
5 miles  south  of  the  camp  C4  were  of  Paleozoic  age. 

Along  the  col  at  the  head  of  Lost  Creek  the  conglomerate  is  rela- 
tively free  of  limestone  and  schist  material,  being  made  up  mainly 
of  igneous  rocks  and  quartz.  Vertical  dips  were  observed  at  a 
number  of  places  and  probably  represent  the  general  attitude  of  the 
beds  in  most  of  this  area.  The  high  dips  and  the  fact  that  the  con- 
glomerate area  is  surrounded  by  Paleozoic  rocks  show  that  the 
younger  beds  have  been  folded  or  faulted  downward  from  their 
former  relative  position,  and  indicate  the  extensive  removal  of  Cre- 
taceous sediments  from  areas  which  they  formerly  occupied.  As  in 
the  other  occurrences,  the  conglomerate  marks  a period  of  littoral  ero- 
sion and  deposition,  and  being  derived  from  the  rocks  upon  which 
it  rests,  its  relation  to  them  is  that  of  unconformity. 

Mendenhall  notes0  the  occurrence  of  unaltered  sediments  at  two 
points  along  Tubutlulik  River.  He  says: 

Eleven  or  twelve  miles  above  the  mouth  of  the  Tubutulik  some  bluish  and 
shaly  sandstones  and  fine  quartz  conglomerates,  entirely  unaltered,  but  dipping 
50°  or  60°  NE.,  outcrops  along  the  river  bank.  Two  or  three  miles  above  this 
exposure  is  another  of  soft,  brown  sandstone  and  fine  conglmerate  with  blue  clay 
shales. 


° Mendenhall,  W.  C.,  Reconnaissance  in  the  Norton  Bay  region,  Alaska,  in  1900,  a 
special  publication  of  the  U.  S.  Geol.  Survey,  1901,  p.  205. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  X 


A.  SANDSTONES  AND  SHALES  OF  SHAKTOLIK  GROUP,  SHAKTOLIK  RIVER. 


B.  CONCRETIONS  IN  SANDSTONES  OF  SHAKTOLIK  GROUP, 


NORTON  BAY-NULATO  REGION,  ALASKA. 


57 


Being  immediately  adjacent  to  the  conglomerate  area  and  having 
suffered  similar  deformation,  these  sediments  probably  belong  with 
the  conglomerate  in  the  same  general  series. 

About  70  miles  east  of  Nulato,  below  the  mouth  of  Melozitna  River, 
a series  of  conglomerates,  grits,  and  shales  is  exposed  along  the 
Yukon.  According  to  Spurr®  these  beds  overlie  Paleozoic  rocks  and 
are  made  up  of  materials  derived  from  them.  Farther  down  the 
Yukon  the  conglomeratic  beds  are  less  important  and  the  series  con- 
sists mainly  of  grits,  sandstones,  and  shales. 

The  determination  of  fossils  collected  by  Atwood  in  1907  from  a 
number  of  horizons  of  this  series  refers  them  all  to  the  Upper 
Cretaceous.  The  Melozitna  locality  may  be  regarded  as  having  been 
at  one  time  the  eastern  margin  of  the  area  of  Mesozoic  deposition,  as 
the  conglomerate  areas  near  Norton  Bay  indicate  the  one  time  western 
margin. 

An  exact  correlation  of  the  conglomerates  of  Melozitna  River  and 
of  the  Norton  Bay  localities  is  not  advocated,  though  by  no  means 
impossible.  The  similarity  of  deposits  means  that  the  same  condi- 
tions which  prevailed  at  one  time  at  one  of  the  localities  prevailed  at 
some  time  during  the  same  general  period  at  the  others,  littoral  con- 
dition necessarily  existing  throughout  the  life  of  the  Mesozoic  Basin. 

SHAKTOLIK  GROUP. 

The  Shaktolik  group,  so  called  after  the  river  of  that  name,  which 
affords  a good  section  of  the  beds,  includes  a thick  series  of  sand- 
stones, shales,  and  grits.  This  name  is  used  to  designate  all  the  beds 
between  the  Ungalik  conglomerate  and  the  top  of  the  sedimentary 
series.  Beds  of  this  group  are  widely  distributed  in  the  sedimentary 
area  and  occupy  most  of  its  space. 

For  convenience  of  description  a separation  into  two  divisions  is 
made,  the  lower  characterized  by  abundance  of  sandstones,  the  upper 
by  the  predominance  of  shales.  Each  will  be  treated  separately  in 
the  order  of  stratigraphic  position  and  localities. 

LOWER  DIVISION  OF  THE  SHAKTOLIK  GROUP. 

Shaktolik  River  and  westward. — Along  Shaktolik  River  and  west- 
ward the  Shaktolik  group  is  made  up  of  alternating  beds  of  sand- 
stone and  shale,  the  latter  aggregating  only  a small  part  of  the  total 
thickness,  (See  PI.  X,  A.)  The  sandstones  are  usually  fine  grained, 
dense,  and  compact,  and  in  some  places  resemble  fine-grained  igneous 
rocks  so  closely  in  apearance  and  in  constituent  minerals  that  their 

° Spurr,  J.  E.,  Geology  of  the  Yukon  gold  district,  Alaska:  Eighteenth  Ann.  Rept.  U.  S. 
Geol.  Survey,  pt.  3,  1898,  p.  189. 


58 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


true  character  was  determinable  only  with  the  aid  of  the  microscope. 
Near  camp  A10  some  of  the  beds  exhibit  a peculiar  concretionary 
structure,  large  spherical  masses  breaking  down  in  concentric  shells 
under  the  blows  of  a light  hammer.  (See  PL  X,  B .)  Another 
unusual  structure  shows  in  the  form  of  weathered  surfaces  seen  at  a 
number  of  places  in  the  sandstone  area,  especially  near  camps  A12 
and  B6.  The  surfaces  mentioned  were  marked  by  linear  striations 
and  flutings  and  by  lobate  forms  suggesting  surface  flow.  (See 
PI.  XI,  A.)  Whether  these  structures  are  original  or  have  been 
developed  by  postdepositional  movements  between  beds  is  not  known. 
Ordinary  ripple  marks  are  absent  in  the  same  localities. 

Microscopically,  the  sandstones  show  a very  even  texture.  The 
sand  grains  are  seldom  well  rounded  and  are  especially  sharp  in  the 
finer-grained  beds.  In  composition  they  include  feldspars,  quartz, 
calcite,  pyroxenes,  amphiboles,  micas,  and  fragments  of  dense  igneous 
rocks.  Most  of  the  material  of  the  sandstones  could  be  derived  from 
the  rock  types  that  are  found  in  the  Ungalik  conglomerate.  Some  of 
the  lower  sandstone  beds  resemble  the  matrix  of  the  conglomerate 
closely,  pointing  to  continued  sedimentation  from  the  same  source. 
Other  beds  approach  limestone  in  composition,  the  sand  grains  being 
mainly  calcite  derived  from  older  limestones.  Calcite  deposited  from 
solution  is  the  principal  cement.  Locally,  secondary  minerals  of  a 
serpentinous  character,  due  to  the  post-depositional  alteration  of 
femic  minerals,  forms  the  cement,  giving  the  rock  a speckled  or 
mottled  appearance.  Such  alteration,  however,  is  not  general,  the 
sandstones  being  remarkable  for  the  unaltered  condition  of  the 
minerals  they  contain.  The  rocks  are  not  highly  colored  as  a rule, 
shades  of  gray  being  most  common  in  fresh  specimens.  Many  of 
the  finer  deposits  are  colored  black  by  carbonaceous  matter  which 
they  contain.  Others  have  reddish  and  reddish-brown  tones,  due  to 
iron  oxides.  Iron  staining  is  common  on  weathered  surfaces. 

The  beds  have  been  extensively  deformed,  close  folding  along 
northeasterly  and  southwesterly  axes  having  occurred.  The  dips 
are  very  high  over  most  of  the  area,  varying  within  a few  degrees 
on  either  side  of  90°  along  the  Shaktolik.  The  stronger  beds  often 
find  topographic  expression  in  prominent  ridges,  but  much  of  the 
topography  has  smooth  rounded  forms  in  which  both  lithology  and 
structure  are  obscured. 

Where  good  exposures  were  observed  much  faulting  was  noted.  In 
other  places,  where  the  structure  wTas  obscure  in  detail,  the  relation 
of  beds  indicated  extensive  displacement.  It  is  safe  to  assume  that 
faulting  on  both  a large  and  a small  scale  has  been  an  important 
part  of  the  deformation  of  the  group.  Schistosity  has  been  developed 
locally  in  places  near  the  structural  axes,  especially  in  the  fine- 
grained carbonaceous  members. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  XI 


A.  SURFACE  MARKINGS  ON  SANDSTONES  OF  SHAKTOLIK  GROUP,  INGLUTALIK  DIVIDE. 


B.  GRANITE  PINNACLES  NORTH  OF  KWINIUK  RIVER. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


59 


The  actual  thickness  of  the  Shaktolik  group  at  any  point  is  not 
known.  A partial  section  exposed  on  the  headwaters  of  the  Inglu- 
talik  River  gives  an  apparent  thickness  of  tens  of  thousands  of  feet. 
Due  allowance  for  the  repetition  of  beds  by  faulting  being  made, 
the  group  is  still  of  very  great  thickness. 

The  lower  or  sandy  division  of  the  Shaktolik  group  overlies  the 
Ungalik  conglomerate  in  apparent  conformity,  and  probably  grades 
upward  without  a break  into  the  upper  division  of  the  group,  which 
consists  mainly  of  black  shales,  and  though  recognized  as  distinct  in 
type,  could  not  be  differentiated  from  the  lower  beds  in  mapping 
without  more  detailed  survey. 

Near  Nulato. — A group  of  sandstones,  shales,  and  grits  with  minor 
lignitic  beds  outcrops  along  Yukon  River  near  Nulato.  These  beds 
have  been  known  as  the  Nulato  sandstone  since  first  visited  by  Dali 
in  1866.  They  are  only  a part  of  a great  series  of  similar  deposits 
which  are  included  in  the  Shaktolik  group.  The  work  in  this  region 
has  not  been  sufficiently  detailed  to  determine  whether  it  will  be  pos- 
sible to  retain  the  name  Nulato  for  one  of  the  formations  of  this 
group. 

The  early  writers,  Dali  and  Spurr,®  considered  these  beds  of  Ter- 
tiary age,  but  subsequent  visits  of  Collier  (1902),  Rollick  (1903), 
and  Atwood  (1907)  and  the  study  of  their  collection  by  Stanton 
and  Knowlton  have  shown  them  to  be  of  Upper  Cretaceous  age.  The 
investigation  of  1909  indicates  that  not  only  are  these  beds  of  Creta- 
ceous age,  but  that  a thickness  of  several  thousands  of  feet  of  beds  of 
undoubtedly  Cretaceous  age  overlies  them. 

In  the  Nulato  section  sandstones  predominate  over  the  shales,  grits, 
and  lignite  beds  that  make  up  the  rest  of  the  group.  Notes  furnished 
by  Atwood  6 show  that  different  types  of  beds  alternate  in  close  suc- 
cession. Fossil  plants,  lignite  deposits,  cross-bedding,  and  ripple 
marks  indicate  shallow  water  conditions  during  part  of  the  period 
of  deposition,  but  alternating  with  these  are  beds  bearing  marine 
shells  and  worm  borings.  Some  of  the  sandstones  are  of  the  even- 
grained, dense  type  common  in  the  Shaktolik  region  and  also  noted 
near  camp  A2.  On  the  whole,  the  sedimentary  rocks  near  Nulato 
show  a greater  variation  in  type  and  indicate  more  changeable  con- 
ditions of  deposition  than  the  rocks  of  the  localities  farther  west. 

The  structure  near  Nulato  is  rather  simple,  the  beds  , dipping  in 
general  to  the  northwest  at  angles  up  to  40°  or  50°.  Locally  the 
beds  are  much  faulted  and  crushed  along  the  axes  of  minor  folds. 
No  definite  measurement  of  the  section  was  attempted,  but  it  must  be 
many  thousand  feet  in  thickness.  The  relations  of  these  beds  to  the 

“Dali,  W.  H.,  Bull.  U.  S.  Geol.  Survey  No.  84,  1892,  pp.  247-248.  Spurr,  J.  E., 
Eighteenth  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  3,  1898,  p.  196. 

b Unpublished  information  ; report  in  preparation. 


60 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


underlying  formations  are  not  evident  at  this  locality.  They  occupy 
the  area  west  of  the  Yukon  to  the  locality  of  camp  A5,  where  they  are 
overlain,  probably  conformably,  by  the  black  shales  which  form  the 
upper  division  of  the  Shaktolik  group. 

Bishop  Rock. — Bishop  Bock  is  a low,  rocky  knob  on  the  Yukon 
about  10  miles  above  the  mouth  of  the  Koyukuk.  It  is  composed  of 
compact  limy  and  shaly  sandstones.  Fossils  collected  here  by  Atwood 
in  1907  were  determined  as  Upper  Cretaceous. 

Near  Melozitna  River. — Overlying  the  basal  conglomerate  corre- 
lated with  the  Ungalik  conglomerate  near  the  mouth  of  the  Melozitna 
Biver  and  downstream  for  30  miles  or  more  a series  of  sandstones, 
grits,  and  shales  outcrops  along  the  Yukon.  In  lithology,  fossils,  and 
relation  to  the  basal  conglomerates  these  beds  are  similar  to  the  Shak- 
tolik group  farther  west  and  are  regarded  as  belonging  to  that  group. 

UPPER  DIVISION  OF  SHAKTOLIK  GROUP. 

The  upper  division  of  the  Shaktolik  group  occupies  the  central 
part  of  the  sedimentary  area  along  the  Xulato-Gisasa  divide  and  west- 
ward to  the  head  of  Shaktolik  Biver.  It  consists  predominantly 
of  black  shales,  but  contains  subordinate  beds  of  calcareous  sandstone. 
Some  of  the  latter  5 miles  west  and  2 miles  south  of  camp  A5  furnish 
invertebrate  fossils  of  Upper  Cretaceous  age. 

This  group  of  beds  probably  represents  a vertical  gradation  into 
finer  sediments  upward  in  the  series,  though  lateral  gradation  is  not 
impossible.  The  shales  are  very  carbonaceous,  indurated,  and  on 
weathering  in  places  break  down  into  pencil-like  fragments.  Schis- 
tosity  has  been  developed  locally  near  structural  axes  in  some  of  the 
more  carbonaceous  members.  The  more  resistant  members  stand  out 
in  strong  ridges;  the  slopes  are  steep,  covered  with  fine  talus,  and 
almost  barren  of  vegetation.  Structurally  the  shales  agree  with  the 
underlying  standstones,  with  which  they  are  conformable.  Black 
shales  accompany  the  sandstones  throughout  the  Shaktolik  group,  but 
the  part  of  the  group  in  which  the}-  predominate  strongly  enough  to 
be  distinguished  as  a separate  division  probably  does  not  include  more 
than  a few  thousand  feet. 

IGNEOUS  ROCKS. 

From  the  foregoing  description  of  the  sedimentary  rocks  it  is  seen 
that  the  Cretaceous  deposits  give  a good  horizon  to  which  to  refer 
different  geological  activities.  The  pebbles  in  the  conglomerate  at 
the  base  of  the  Cretaceous  show  what  rocks  were  in  existence  when 
the  beds  were  deposited,  and  all  igneous  rocks  cutting  the  Cretaceous 
must  be  later  than  the  beds  they  cut.  For  this  reason  the  igneous 
rocks  of  the  region  have  been  divided  into  pre-Cretaceous  and  post- 
Cretaceous.  Each  of  these  main  subdivisions  contains  rocks  of  differ- 


NORTON  BAY-NULATO  REGION.  ALASKA. 


61 


ent  mineralogic  composition  and  field  relations  and  was  formed  under 
different  conditions;  both  show  intrusive  and  effusive  rocks  and 
afford  much  material  for  detailed  petrographic  studies,  which,  how- 
ever, have  not  been  attempted  in  the  preparation  of  this  report. 

The  larger  areas  of  pre-Cretaceous  igneous  rocks  are  the  flanks  of 
the  Kaiyuh  Hills,  the  Buckland-Kiwalik  divide,  the  Bendeleben  and 
Darby  ranges,  the  region  around  Bluff,  and  numerous  small  areas 
in  the  metamorphic  complex.  The  larger  areas  of  post-Cretaceous 
igneous  rocks  in  the  Yukon  Valley  are  at  the  mouth  of  the  Koyukuk 
and  south  of  Kaltag;  in  Seward  Peninsula  they  are  in  the  Koyuk 
River  Basin,  especially  in  the  central  portion,  extending  to  the  head  of 
Kiwalik  River;  at  the  very  head  of  the  Koyuk,  extending  to  Noxa- 
paga  River;  and  at  the  lower  part  of  East  Fork,  extending  into  the 
Buckland  River  basin. 

PRE-CRETACEOUS  IGNEOUS  ROCKS. 

In  the  long  time  represented  by  the  pre-Cretaceous  history  of  the 
region  there  are  two  distinctly  marked  periods  of  much  geological 
significance.  One  of  these  preceded  the  dynamic  metamorphism  of 
the  region  and  the  other  followed  it.  Rocks  formed  in  the  earlier 
period  show  structures  due  to  this  deformation,  whereas  those  formed 
afterwards  have  not  been  much  metamorphosed.  A division  of  the 
pre-Cretaceous  igneous  rocks  into  two  groups,  metamorphic  and  non- 
metamorphic,  may  be  made,  and  this  grouping  will  be  followed  in 
this  report. 

METAMORPHIC  IGNEOUS  ROCKS. 

Rocks  of  igneous  origin  earlier  than  the  period  of  metamorphism 
have  been  recognized  in  many  parts  of  the  region.  The  four  larger 
areas  mapped  are  in  the  Kaiyuh  Hills,  east  of  the  Darby  Range,  in 
the  belt  extending  northward  from  Bluff  in  the  western  part  of  the 
area,  and  north  of  Omilak  Creek.  All  of  these  areas  have  features 
more  or  less  in  common,  but  it  is  by  no  means  certain  that  all  of  them 
have  been  formed  at  the  same  time  or  are  mineralogicallv  identical. 
Furthermore,  there  is  but  little  doubt  that  other  metamorphic  igne- 
ous rocks  might  be  recognized  if  investigations  had  been  carried  on 
in  greater  detail,  and  doubtless  some  of  the  area  mapped  as  undiffer- 
entiated metamorphic  rocks  is  formed  of  igneous  rocks. 

Reference  has  already  been  made  on  page  40  to  the  belts  of  meta- 
morphic igneous  rocks  occurring  on  both  flanks  of  the  Kaiyuh  Hills. 
These  were  described  by  Maddren  as  consisting  of  diabasic  rocks  of 
probably  effusive  character.  They  are  less  metamorphosed  than  the 
older  sedimentary  rocks  which  form  the  Kaiyuh  Hills  on  which  these 
ancient  lavas  probably  lie  unconformably. 


62 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


In  Seward  Peninsula  the  metamorphic  igneous  rocks  are  usually 
greenish  in  color,  and  differ  much  in  degree  of  foliation ; in  the  cen- 
tral part  of  the  peninsula  they  are  high  in  soda  and  low  in  quartz. 
Usually,  where  schistose,  the  rocks  have  had  secondary  albite  de- 
veloped and  become  greenish  feldspathic  schists.  Although  the  feld- 
spathic  character  may  be  produced  in  other  ways,  as,  for  instance,  by 
the  contact  effect  of  igneous  rocks,  it  is  believed  that  in  a large  way 
the  presence  in  this  field  of  highly  feldspathic  schists  is  strongly 
suggestive  of  the  igneous  origin  of  the  rocks  in  question,  and  this  is 
assumed  to  be  true  if  contradictory  evidence  was  not  observed. 

The  clearest  evidence  concerning  the  greenstones  and  associated 
feldspathic  schists  is  afforded  by  the  cliff  exposures  along  the  east 
coast  of  the  Darby  Peninsula.  Along  this  part  of  the  coast  are 
numerous  dikes  and  sills  of  basic  composition  cutting  the  Paleozoic 
rocks.  A particularly  clear  example  of  a greenstone  intrusion  of  this 
sort  is  shown  in  Plate  VIII,  A (p.  46) . At  this  place,  which  is  between 


Figure  4. — Relation  of  greenstone,  limestone,  and  slates,  east  coast  Darby  Peninsula. 
a,  Soil  and  waste ; b,  limestone  ; c,  greenstone ; d,  black  slates ; e,  talus. 

the  Kuiuktulik  and  Walla  Walla,  light  and  dark  banded  Paleozoic 
limestones  have  an  unusually  low  dip.  These  have  been  intersected 
by  nearly  vertical  cleavage,  and  parallel  to  this  cleavage  the  green- 
stones have  been  intruded.  The  large  white  masses  showm  in  the 
picture  are  calcite  veins  of  later  formation,  probably  contemporaneous 
with  the  succeeding  period  of  mountain  building. 

The  structural  relations  of  the  greenstones  are  in  places  complex 
and  show  that  these  rocks  have  been  subjected  to  considerable  dis- 
turbance. Figure  4 illustrates  an  exposure  of  slates,  limestones,  and 
greenstones  on  the  eastern  coast  of  the  Darby  Peninsula  about  mid- 
way between  the  mouth  of  the  Miniatulik  and  the  Kuiuktulik.  The 
greenstone  intruded  slates  and  limestones  and  has  subsequently  been 
folded  into  a number  of  appressed  folds.  Thrust  faulting  then  took 
place  along  the  plane  indicated  so  that  the  south-dipping  limestone 
was  superposed  on  the  greenstone  and  the  slates  giving  a section  as 
indicated  in  the  figure.  The  axis  of  folding  at  this  place  is  about 
N.  70°  E.  and  the  folds  pitch  toward  the  west. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


63 


In  many  places  the  deformation  and  accompanying  metamorphism 
of  the  greenstones  has  gone  so  far  that  the  original  characters  of  the 
rocks  are  obliterated  and  it  is  not  certain  what  origin  is  to  be  as- 
signed. Brooks,  in  a study  of  the  Bluff  region,  found  schistose  rocks 
which  seemed  to  show  by  their  areal  relations  igneous  rather  than 
sedimentary  characters.  Concerning  these  schists  he  says : * 

Mica  schists  occur  as  irregular  masses  within  the  limestone  belts  and 
although  they  do  not  differ  lithologically  in  any  very  essential  way  from  the 
schists  believed  to  be  of  sedimentary  origin,  their  mode  of  occurrence  strongly 
suggests  that  they  are  altered  intrusions.  The  most  striking  example  of  this 
is  seen  in  the  cliff  exposures  just  east  of  the  mouth  of  Daniels  Creek  (fig.  5). 
Here  an  irregular  mass  of  mica  schist  is  inclosed  in  limestone  walls.  Lines  of 
faulting  have  obscured  the  original  relations  of  the  two  rocks,  but  the  outline 
of  the  schist  mass  is  very  suggestive  of  an  intrusion.  Further  evidence  of  the 
intrusive  character  of  some  of  these  schists  is  found  in  the  fact  that  at  various 
localities  the  limestone  walls  near  the  contact  with  the  schists  are  more  or 
less  metamorphosed.  These  facts,  together  with  the  irregular  distribution  of 
the  schists,  indicate  an  igneous  origin,  though  it  must  be  confessed  that  the 
evidence  is  by  no  means  conclusive. 


Figure  5. — Cliff  exposures  near  mouth  of  Daniels  Creek,  Bluff  region. 

At  several  places  the  actual  gradation  from  an  unquestionably 
igneous  rock  into  a green  feldspatliic  schist  has  been  observed. 
Here  and  there  in  the  hills  south  of  camp  C15  are  examples  of  this 
sort,  and  although  it  is  not  intended  to  assert  that  all  the  feldspatliic 
schists  are  of  this  origin,  it  is  certain  that  many  if  not  most  of  them 
are  formed  in  this  way. 

An  exposure  of  metamorphosed  igneous  rock  is  afforded  near  the 
Omilak  mine.  Figure  6 shows  the  general  geology  in  the  neighbor- 
hood of  the  mine,  with  the  intrusive  cutting  across  the  western  limb 
of  the  limestone.  Plate  IX,  A (p.  50),  supplements  this  map  by 
showing  the  general  appearance  of  the  same  hill  from  the  south.  In 
this  view  the  dark  area,  in  the  center  of  the  view  is  the  igneous  rock, 
and  an  apophysis  is  represented  by  the  dark  band  which  cuts  across 
the  right-hand  limestone  area.  From  a study  of  this  rock  under  the 

a Collier  and  others,  The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska : Bull. 
U.  S.  Geol.  Survey  No.  328,  1908 — The  Bluff  Region,  pp.  285-280. 


64 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


microscope  it  has  been  determined  that  it  consists  of  olivine,  a light- 
colored  amphibole  probably  tremolite,  very  abundant  light-green 
garnet  and  muscovite,  with  some  accessory  ilmentite  and  apatite  and 
secondary  serpentine.  This  is  an  unusual  phase  of  the  greenstone 
series  and  has  not  been  recognized  elsewhere. 

NONMET  AMORPHIC  IGNEOUS  ROCKS. 

There  are  three  large  areas  of  pre- Cretaceous  nonmetamorphic 
igneous  rocks  to  which  attention  should  be  called.  These  are  the 
Darby  Range,  the  Kiwalik-Buckland  divide,  and  the  Bendeleben 
Mountains.  In  addition,  several  smaller  areas,  such  as  Iviwalik 
Mountain,  are  found  in  the  region,  but  as  they  show  the  same  features 


as  the  igneous  rocks  in  the  larger  areas  they  will  not  be  described 
separately. 

Mendenhall,  who  studied  portions  of  the  Darby  Range  in  some 
detail,  says : ° 

Cape  Darby  and  a broad  belt  of  country  extending  55  miles  northward  from 
it  with  a maximum  width  of  about  12  miles  is  occupied  by  a great  intrusive 
body  of  granite  and  granitized  rock  which  exhibits  considerable  variation  in 
texture  and  mineralogical  composition,  but  is  regarded  as  belonging  to  one 
geological  body. 

A few  miles  below  Cheenik,  along  the  eastern  shore  of  Golofnin  Bay,  the  rock 
is  diorite  porphyry  with  large  tabular  phenocrysts  of  andesine  or  andesine- 
oligoclase,  some  colorless  pyroxene,  and  abundant  hornblende  in  part  at  least 
secondary.  Quartz  is  present  but  often  in  very  inconsiderable  amounts,  and 

° Mendenhall,  W.  C.,  op.  cit.,  p.  204. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


65 


titanite  is  an  inconspicuous  accessory.  This  phase  or  a slightly  more  acid  one 
is  rather  largely  represented  in  this  portion  of  the  mass  extending  at  least 
5 to  6 miles  east  from  its  western  border. 

Near  the  eastern  edge  of  the  northern  part  of  the  area  in  the  Tubutulik 
Valley  the  rock  appears  as  a coarsely  crystalline  aggregate  of  pale  brownish 
orthoclase  and  smoky  quartz  with  a little  biotite.  A gneissoid  phase  of  the 
same  rock  occurs  along  the  western. side  of  its  western  limit. 

Distinct  contact  phenomena  in  the  schists  and  slates  while  sometimes  present 
are  not  so  abundant  as  one  would  expect.  The  inference  is  that  the  intrusion 
was  slow  and  deep-seated  and  affected  the  intruded  rock  generally;  rather  than 
locally.  This  inference  finds  support  in  the  coarse  texture  and  porphyritic 
character  of  the  diorite  even  at  its  borders. 

In  1909  it  was  the  intention  of  the  party  to  avoid  revisiting  the 
areas  already  studied  by  Mendenhall,  so  that  in  but  few  instances 
does  the  work  overlap.  From  this  later  study  it  was  found  that  the 
areal  distribution  as  already  given  by  Mendenhall  required  but  slight 
modification,  but  that  the  number  of  different  kinds  of  rock  was  more 
complex  than  his  report  indicated.  There  are  at  least  two  distinct 
types  of  granite,  one  with  marked  porphyritic  development  and  the 
other  of  even  grain. 

The  largest  area  of  the  porphyritic  granite  is  in  the  Kwiniuk  basin 
extending  from  a little  east  of  camp  C14  to  at  least  4 miles  north  of 
camp  C15.  In  addition,  the  same  rock  was  found  on  the  seacoast  at 
the  mouth  of  Carson  Creek  and  is  probably  the  same  as  the  granite 
with  brownish  feldspar  described  in  the  northern  end  of  the  belt. 
This  rock  is  characterized  by  a coarse-grained  mass  of  quartz,  ortho- 
clase, and  a little  biotite,  the  various  grains  averaging  about  0.2 
inch  in  diameter,  with  large  orthoclase  crystals  averaging  about  1^ 
inches  in  length  scattered  abundantly  through  the  rock.  A few  in- 
clusions of  diorite  were  found  in  the  porphyritic  granite,  one  of 
which  showed  calcite-filled  cavities,  probably  amygdaloidal  in  origin. 
Typically  the  porphyritic  granite  weathers  into  fantastic  knobs  and 
pinnacles  similar  to  those  shown  in  Plate  XI,  B (p.  58).  This 
feature  is  also  shown  more  extensively  developed  in  Plate  III,  A 
(p.  30),  the  pinnacles  shown  being  probably  of  granite  of  this  type. 

The  even-grained  granite  may  be  of  the  same  age  as  the  porphy- 
ritic granite.  If  this  is  the  case  the  two  may  have  consolidated  under 
different  conditions.  It  does  not  seem  evident  from  the  field  rela- 
tions, however,  that  the  porphyritic  rock  cooled  under  essentially 
different  conditions  except  that  the  porphyritic  granite  forms  larger 
masses  than  the  finer-grained  type.  Mineralogically  the  even-tex- 
tured granite  consists  of  quartz,  both  orthoclase  and  plagioclase  feld- 
spar and  biotite.  Dark-colored  silicates,  although  present,  form  but 
a relatively  small  amount  of  the  rock.  It  occurs  usually  in  rather 
narrow  dikes,  and  no  large  area  of  this  type  is  known  in  the  Darby 
Range.  Dikes  of  this  granite  have  already  been  noted  in  previous 
71469°— Bull.  449—11 5 


66 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


pages  as  cutting  the  Paleozoic  rocks  at  many  places.  Plate  VIII,  B 
(p.  46),  shows  a nearly  \rertical  granite  dike,  the  light-colored  rock 
(on  which  the  hammer  rests)  cutting  across  the  structure  of  the  meta- 
morphic  limestone  and  sending  apophyses  into  it. 

Diorite  also  occupies  large  areas  in  the  Darby  Range.  In  compo- 
sition it  ranges  from  a normal  amphibole  jhagioclase  rock  to  one  con- 
taining quartz  and  orthoclase  in  addition  to  the  usual  constituents. 
The  plagioclase  is  apparently  andesine-oligoclase ; that  is,  about  mid- 
way in  the  soda-lime  series.  Accessory  apatite,  titanite,  muscovite, 
and  metallic  minerals  in  small  amounts  were  noted  in  several  ex- 
amples of  this  rock  studied  microscopically. 

From  the  fact  that  inclusions  of  diorite  are  found  in  the  porphy- 
ritic  granite,  it  is  assumed  that  the  latter  is  younger  than  some  of  the 
diorite.  Plate  XII,  A , however,  shows  that  there  is  more  than  one 
diorite  represented  in  the  region.  In  this  view  the  large  light- 
colored  area  on  which  the  hammer  rests  is  porphvritic  granite  with 
numerous  inclusions  of  diorite.  Unfortunately  in  this  picture  the 
further  fact  that  the  porphyritic  granite  itself  is  an  inclusion  in 
the  dark  igneous  rock  which  forms  the  lower  left-hand  portion 
of  the  view  is  not  shown,  although  this  fact  is  clearly  proved  by  the 
exposure  in  the  field.  It  should  further  be  noted  that  in  this  later 
diorite  intrusion  are  inclusions  of  the  older  diorite.  Although  the 
similar  color  makes  the  two  diorites  difficult  to  distinguish  in  this 
view,  several  of  the  older  diorite  inclusions  may  be  recognized  at 
the  extreme  left  below  the  porphyritic  granite-diorite  contact. 

In  addition  to  the  granites  and  diorites  there  are  several  other 
types  of  rocks,  the  distribution  and  relations  of  which  are  not  suffi- 
ciently clear  to  allow  their  differentiation.  One  of  these  rocks  is  a 
quartz  porphyry  with  double  terminated  quartz  crystals  and  plagio- 
clase as  phenocrysts  in  a ground  mass  of  quartz  and  orthoclase  in  a 
micropegmatitic  intergrowth.  Accessory  green  hornblende,  apatite, 
and  magnetite  with  secondary  kaolin,  muscovite  and  chlorite  were 
also  present.  This  type  of  rock- was  found  particularly  in  the  hills 
south  of  camp  C13  in  the  divide  between  the  Ivwiniuk  and  the 
Etchepuk. 

Another  unusual  type  of  rock  forms  a large  area  in  the  Ivwiniuk 
divide  south  of  camp  C13,  extending  westward  an  undetermined 
distance  and  soutlrvvard  to  beyond  camp  C14.  It  is  dark  colored,  with 
lath-shaped  phenocrysts  an  inch  or  more  in  lengtji  of  orthoclase  feld- 
spar. The  groundmass  is  composed  of  orthoclase,  albite,  oligoclase, 
green  hornblende,  segirine  augite,  and  biotite,  with  accessory  titanite 
in  great  abundance,  and  some  apatite.  Usually  the  pyroxene  forms 
core?  around  which  amphibole  has  been  developed,  probably  by  the 
alteration  of  the  pyroxene.  The  absence  of  quartz  and  the  high  soda 
content  distinguish  this  rock  from  the  others  already  described. 


U.  S.  GE0L03ICAL  SURVEY 


BULLETIN  449  PLATE  XII 


B.  VENATION  IN  LIMESTONE,  EAST  COAST  OF  DARBY  PENINSULA. 


67 


NORTON  BAY-NULATO  REGION,  ALASKA. 

Another  unusual  type  of  igneous  rocks  was  found  on  the  hill  about 
three- fourths  of  a mile  north  of  camp  C22  on  a branch  of  Kachauik 
Creek.  It  is  rather  closely  associated  with  rocks  of  the  fine-grained 
granite  type,  but  the  precise  relations  are  not  known.  It  is  a light- 
colored  fine-grained  rock  with  a few  scattered  phenocrysts  of  nephe- 
line  and  sanidine.  In  the  ground  mass,  which  is  very  fine-grained, 
are  albite,  nepheline,  sanidine,  segirine  augite,  fluorite,  eudialyte, 
riebekite,  and  biotite.  The  high  soda  content  suggests  correlation 
with  the  other  soda -rich  rock  previously  described,  which  was  also 
wanting  in  quartz. 

Rocks  similar  to  the  Darby  range  intrusives,  with  the  exception 
of  the  last  three  phases,  have  been  found  in  the  pebbles  of  the  Cre- 
taceous conglomerate,  and  no  hesitation  is  felt  in  ascribing  them  to 
an  age  prior  to  the  Cretaceous.  It  is  also  evident  from  the  studies 
in  the  field  that  all  of  these  rocks  cut  the  Paleozoic  series  and  have 
not  been  dynamically  metamorphosed  to  any  marked  extent.  That 
there  have  been  several  periods  of  intrusive  activity  is  shown  by  the 
relations  of  the  diorites  and  porphyritic  granites  described  on  page 
66.  Whether,  however,  these  periods  were  separated  by  any  con- 
siderable time  interval  or  whether  they  really  mark  only  one  major 
period  of  intrusive  activity  has  not  been  determined. 

Few  new  facts  of  importance  have  been  added  to  those  already  pub- 
lished by  Moffit  concerning  the  igneous  rocks  of  the  Kiwalik-Buckland 
divide.  According  to  this  geologist  ° — 

Much  the  larger  part  of  the  undissected  mass  which  forms  the  divide  between 
the  drainages  of  the  Kiwalik  and  the  Buckland  Rivers,  and  contains  the  highest 
elevations  of  the  northeastern  part  of  the  peninsula,  is  made  up  of  light-colored 
granular  rocks  and  andesites  associated  especially  toward  the  outer  portions 
of  the  area  with  basalts  and  diabases. 

In  crossing  the  main  part  of  the  mass  from  the  westward  after  leaving  the 
highly  metamorphic  rocks  of  the  Kiwalik  Valley  one  meets  first  with  basic 
rocks  of  the  basaltic  and  diabasic  type,  followed  by  andesites  which  are  well 
developed  and  form  a large  part  of  the  ridge ; finally,  in  the  central  portion  of 
the  complex,  and  forming  a core  for  the  whole,  are  discontinuous  areas  of  more 
siliceous  rocks,  including  a number  of  different  varieties  of  granites,  monzonites, 
and  quartz  diorites.  Hornblende  is  the  prevailing  dark  mineral  of  the  granites, 
but  at  times  biotite  takes  its  place.  By  a decrease  in  the  amount  of  quartz 
the  granites  approach  syenites  in  composition,  such  phases  being  characterized 
by  the  abundance  and  larger  size  of  ortlioclase  crystals,  which  usually  show 
Carlsbad  twinning  and  have  a rough  parallel  arrangement  with  the  small  inter- 
vening spaces  filled  with  hornblende,  biotite,  and  a small  amount  of  quartz. 
Titanite  is  abundant. 

An  unusual  and  highly  interesting  type  was  observed  in  the  most  southerly 
area  of  the  granular  rocks.  The  hand  specimens  show  a dark-gray  rock,  com- 
posed of  abundant  large  tabular  feldspar  crystals  with  a small  amount  of  dark- 

° Moffit,  F.  H.,  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska : Bull.  U.  S. 
Geol.  Survey  No.  247,  1905,  pp.  27-31. 


68 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


greenish  fine-grained  filling.  In  thin  section  the  rock  is  seen  to  consist  of  large 
crystals  of  orthoclase  feldspar  with  a microscopic  intergrowth  of  parallel  plagio- 
clase  plates  embedded  in  a groundmass  of  segirine-augite,  melanite,  and  small 
scattered  plagioclase.  The  three  last-named  minerals  fill  spaces  between  the 
large  orthoclase  crystals,  which  are  very  subordinate  in  volume  to  the  spaces 
occupied  by  the  crystals  themselves.  Titanite  and  apatite  are  present,  and  a 
cloudy  zeolitic  decomposition  product  appears  at  times.  The  rock  corresponds 
very  closely  in  appearance  and  composition  with  the  garnet-pyroxene  malig- 
nites,  which  Lawson  has  described,  from  Maligne  River  in  Ontario. 

The  diorites  present  no  unusual  features.  They  are  nearly  always  of  a light- 
gray  color  and  are  sometimes  porphyritic.  The  prevailing  feldspar  is  plagio- 
clase with  zonal  structure.  Some  quartz  is  always  present  and  the  dark 
mineral  is  usually  hornblende,  but  at  times  biotite.  In  one  or  two  instances  a 
well-developed  flow  structure  was  seen  in  large  blocks  of  the  diorite  which 
were  cut  by  small  granitic  or  aplitic  dikes  largely  feldspar. 

Monzonites  intermediate  in  composition  between  granites  and  quartz  diorites 
are  frequent.  Orthoclase  and  plagioclase  predominate  while  hornblende,  bio- 
tite, and  quartz  are  present ; also  titanite,  magnetite,  apatite,  and  occasionally 
zircon.  All  the  granular  rocks  of  this  region  are  abundantly  supplied  with 
titanite  which  may  often  be  easily  seen  in  the  hand  specimen  and  is  very 
noticeable  under  the  microscope. 

Andesites  are  abundant  in  the  Kiwalik-Buckland  divide  and  are  probably 
the  surface  representative  of  an  igneous  magma  corresponding  in  composition 
to  the  deep-seated  diorites  and  monzonites.  As  already  stated,  they  occupy, 
where  observed  by  the  writer,  a position  intermediate  between  the  basic  rocks 
of  the  western  side  of  the  ridge  and  the  central  acid  ones  and  form  a large 
part  of  the  watershed.  They  are  of  a dark-gray  or  greenish  color  and  on  an 
exposed  surface  have  a spotted  appearance  due  to  the  alteration  of  the  feld- 
spar phenocrysts.  Both  hornblende  and  pyroxene  varieties  were  seen,  the  latter 
containing  considerable  olivine  in  addition  to  pyroxene  and  showing  the  sec- 
ondary mineral  iddingsite.  Alteration  of  pyroxene  to  hornblende  was  also 
observed.  The  feldspar  is  a basic  variety,  labradorite  or  sometimes  anorthite, 
giving  as  alteration  products  chlorite  and  epidote. 

Andesite  breccias  were  found  at  various  localities. 

Little  can  be  added  from  the  work  of  1909  to  these  descriptions 
and,  although  it  has  been  possible  in  a measure  to  extend  the  map- 
ping of  these  rocks,  the  additional  data  are  so  clearly  evident  on 
the  map  that  further  description  is  not  required,  except  to  note 
that  the  extension  south  of  the  Kovuk  is  formed  mainly  of  rocks  of 
the  effusive  rather  than  of  the  intrusive  t}qoe..  It  should  also  be 
pointed  out  that  whereas  the  intrusive  rocks,  which  form  the  core 
of  the  Kiwalik-Buckland  divide,  are  in  all  respects  similar  to  the 
igneous  rocks  in  the  Darby  Range,  the  effusive  rocks  which  occur 
along  the  flanks  have  no  recognized  representative  in  the  latter 
mountains. 

The  igneous  rocks  of  the  Bendeleben  Mountains  so  far  studied 
belong  mainly  to  the  group  of  granites,  and,  although  here  and  there 
these  rocks  show  gneissic  phases,  it  is  believed  that,  as  a group,  they 
are  essentially  contemporaneous  and  are  later  than  the  post-Paleozoic 
deformation.  Lithologically  the  granites  are  indistinguishable  from 


NORTON  BAY-NULATO  REGION,  ALASKA. 


69 


the  granites  of  the  Darby  or  Buckland-Kiwalik  ranges,  and  it  is  as- 
sumed that  such  close  similarity  could  not  have  occurred  unless  all 
these  rock's  had  been  derived  from  essentially  the  same  magma  at 
nearly  the  same  time.  It  is  on  the  basis  of  this  assumption  that  the 
pre-Cretaceous  age  of  the  granite  masses  in  the  Bendeleben  Moun- 
tains is  postulated. 

In  the  Bendeleben  Mountains  the  geologic  mapping  is  extremely 
conventionalized  and  the  reader  should  regard  this  part  of  the  map 
as  suggesting  the  kind  of  geology  probably  to  be  expected  rather 
than  as  a faithful  portrayal  of  the  actual  areal  distribution  of  the 
different  types  of  rock.  As  mapped,  however,  this  area  serves  to 
bring  out  the  fact  that  there  are  numerous  large  bodies  of  igneous 
rock,  in  places  many  miles  in  diameter,  and  also  that  there  is  a 
most  complex  network  of  small  dikes  and  sills,  many  of  which  are 
from  a few  inches  to  a few  feet  wide.  The  lithology  and  mineralogy 
of  the  two  types,  however,  do  not  materially  differ.  Some  of  the 
small  sills  and  dikes  have  as  coarse  texture  as  the  more  central  parts 
of  the  larger  masses.  Both  modes  of  occurrence  are  typically  quartz- 
feldspar  granites  with  some  dark  silicates  and  various  accessory 
minerals.  Even  in  the  gneissic  phases,  Collier  a states  the  structure 
must  either  be  original  or  else  the  whole  rock  has  recrystallized,  for  the 
microscopic  examination  shows  little,  if  any,  evidence  of  distortion  or 
dynamic  movement.  In  other  places  it  is  evident  that  the  apparent 
gneissic  structure  is  due  to  the  replacement  of  adjacent  schists,  some 
of  which  are  so  thoroughly  saturated  by  the  igneous  rock  that  much  of 
the  original  character  has  been  destroyed. 

The  contacts  between  the  granites  and  the  schists,  however,  are 
not  always  vague  and  ill  defined,  but  in  places  are  sharp  and  clear- 
cut.  These  differences  are  probably  to  be  explained  by  the  varia- 
tions in  composition  of  the  wall  rocks  and  also  by  the  different  depths 
of  burial  of  the  schists  when  the  intrusions  took  place. 

Associated  with  the  normal  granites  are  a few  rocks  of  pegmatitic 
and  aplitic  phases  which  seem  to  have  marked  the  later  or  closing 
stages  of  the  intrusive  period.  In  the  pegmatities  tourmaline  is  in 
places  an  important  accessory  mineral.  One  such  pegmatite  in  par- 
ticular was  noted  on  Birch  Creek  near  the  pass  to  the  head  of  Niukluk 
River.  Mica  in  plates  sometimes  6 inches  or  more  in  diameter  is 
found  in  the  pegmatites.  A locality  where  particularly  large  mica 
plates  have  been  reported  is  near  Oregon  Creek,  a tributary  of  Fish 
River  heading  on  the  south  slopes  of  the  Bendeleben  Mountains,  and 
some  attempts  have  been  made  to  develop  a commercial  deposit. 

At  a few  places  dark  basic  dikes  have  been  reported  cutting  the 
granites.  Whether  these  belong  to  the  pre-Cretaceous  igneous  rocks 

° Collier,  A.  .T.,  and  others,  The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska  -• 
Bull.  U.  S.  Geol.  Survey  No.  328,  1908,  p.  104. 


to  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

similar  to  the  latest  dioritic  intrusion  noted  in  the  Darby  range  or 
whether  they  are  post-Cretaceous  is  not  known.  They  form  rela- 
tively narrow  dikes  and  occupy  such  small  areas  in  the  Bendeleben 
Mountains  and  so  little  is  known  about  them  that  they  will  not  be 
treated  further  in  this  report. 

POST- CRETACEOUS  IGNEOUS  ROCKS. 

Later  than  the  deposition  of  Cretaceous  sediments,  intrusive  and 
extrusive  igneous  rocks  have  been  formed.  As  has  already  been 
noted,  the  main  areas  of  the  latter  are  in  the  Yukon  and  Koyuk  basins 
and  the  only  area  of  the  intrusive  rocks  studied  is  in  the  lower  part 
of  the  Ungalik  Valley. 

INTRUSIVE  ROCKS. 

Christmas  Mountain,  east  of  the  lower  part  of  Ungalik  River,  is 
the  only  center  of  post-Cretaceous  intrusion  noted.  This  prominent 
landmark  is  formed  of  an  igneous  complex,  the  relations  of  the  vari- 
ous members  being  uncertain.  The  series  of  rocks  grade  according 
to  texture  from  augite  andesite  to  augite  diorite.  The  main  mass  of 
the  mountain  is  of  the  more  granular  type,  in  the  coarsest  phases  hav- 
ing crj^stals  up  to  3 millimeters  in  diameter.  This  coarse  phase  con- 
tains abundant  plagioclase,  which  has  been  determined  to  be  albite, 
andesine,  and  labradorite.  Augite,  biotite,  and  olivine  are  also 
present  as  important  constituents.  Among  the  accessory  minerals 
are  magnetite  and  apatite,  the  latter  being  notably  pleochroic. 
Secondary  biotite,  chlorite,  sericite,  and  serpentine  have  also  been 
recognized  in  this  section. 

Associated  with  the  diorites  in  the  western  part  of  the  area,  prob- 
ably in  the  form  of  a dike,  is  a porphyritic  rock  composed  of  ortho- 
clase,  plagioclase,  biotite,  and  augite  as  the  essential  constituents,  and 
with  pyrite  and  calcite  as  accessory  or  secondary  minerals.  The 
phenocrysts  in  this  rock  are  mainly  feldspar,  but  a few  are  of  light- 
green  pyroxene. 

The  clearest  evidence  concerning  the  age  of  these  rocks  is  afforded 
by  exposures  along  the  Ungalik,  near  camp  A16,  where  dikes  of 
essentially  similar  composition  are  found  cutting  the  Ungalik  con- 
glomerate. Subsequent  faulting  has  dislocated  the  dikes,  but  the 
amount  of  displacement  indicated  is  not  more  than  a few  yards. 
Thin  sections  of  specimens  from  these  dikes  show  a light-colored 
porphyritic  rock  with  phenocrysts  of  oligoclase  and  a monoclinic 
amphibole.  In  the  main  the  ground  mass  has  a trachvtic  texture  and 
is  composed  largely  of  oligoclase  and  albite,  with  accessory  apatite. 
Calcite,  quartz,  magnetite,  kaolin,  muscovite,  and  limonite,  all  prob- 
ably secondary,  were  recognized.  The  limonite  is  in  more  or  less 
rectangular  patches,  which  points  to  its  having  been  derived  from 


NORTON  BAY-NULATO  REGION,  ALASKA. 


71 


the  alteration  of  ferromagnesian  minerals  originally  in  this  rock.  At 
Bonanza  Creek  an  intrusion  of  similar  character  cutting  the  black 
slates  was  found. 

On  the  Shaktolik,  at  camp  A12,  a fine-grained  quartz  porphyry 
was  recognized  in  the  float,  but  the  fragments  were  well  rounded,  as 
though  they  had  been  carried  far,  and  there  is  no  clue  as  to  where  the 
rock  outcrops.  The  presence  of  this  float,  however,  strongly  points 
to  the  conclusion  that  it  is  from  an  intrusive  later  than  the  Cretaceous 
sediments.  It  is  probable  that  a more  extensive  exploration  of  this 
region  would  show  intrusive  centers  like  that  of  Christmas  Mountain 
in  other  parts  of  the  Nulato-Norton  Bay  region. 

EFFUSIVE  ROCKS. 

Effusive  rocks  of  late  geologic  age  are  found  at  many  places.  All 
of  there  flows  are  probably  not  contemporaneous,  but  when  they  are 
considered  in  a broad  way  it  is  believed  that  they  mark  essentially 
one  period  of  volcanism.  Thus,  though  many  years  may  have  elapsed 
between  successive  flows,  even  in  the  same  district,  there  seems  to  be 
strong  reason  for  correlating  them  together  as  one  group  and  regard- 
ing them  all  in  a geologic  sense  as  synchronous.  Although  the  rocks 
described  in  this  section  are  essentially  lavas  or  surface  flows,  there 
are,  of  course,  here  and  there  dikes  by  which  these  rocks  were  brought 
to  the  surface.  All  of  these  rocks  are  characteristically  olivine 
basalts  with  a vesicular  structure. 

The  eastern  locality  of  the  post-Cretaceous  effusives,  the  one  near 
the  mouth  of  the  Ivoyukuk,  was  first  carefully  described  by  Spurr,° 
from  whose  account  the  following  quotation  is  taken : 

Megascopically  (the  rock)  is  dark  green  and  amygdaloidal,  the  amygdules 
being  partly  quartz  and  calcite.  Under  the  microscope  a large  vesicle  whose 
walls  are  lined  with  serpentine  is  filled  with  barite  in  interlocking  plates. 
Many  small  ovoidal  vesicles  are  lined  with  serpentine  and  filled  with  chlorite. 
These  are  comparatively  large  phenocrysts  which  are  now  pseudomorphed  by 
calcite  and  serpentine,  but  were  probably  originally  olivine.  The  structure  of 
the  groundmass  is  as  if  originally  composed  of  holocrystalline  plagioclase  and 
augite.  The  augite  is  abundant  and  not  greatly  decomposed  but  the  plagioclase 
crystals  have  been  replaced  by  pseudomorphs  of  some  other  mineral  in  part,  at 
least,  isotropic.  The  rock  is  evidently  a true  olivine  basalt  considerably  altered 
and  decomposed. 

Although  the  lavas  represented  in  the  Yukon  Valley  to  the  south  of 
this  place  have  not  been  described  in  detail  they  probably  belong  to 
the  same  period  of  volcanic  activity.  Similar  lavas  have  been  re- 
ported by  Collier  along  the  river  south  of  Kaltag,  but  their  extent 
has  not  been  determined  and  there  are  no  published  descriptions  of 

a Spurr,  J.  E.,  Geology  of  the  Yukon  gold  district,  Alaska : Eighteenth  Ann.  Rept.  U.  S. 
Geol.  Survey,  pt.  3,  1898,  pp.  245-246. 


72 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


the  occurrences.  It  seems  probable,  however,  from  the  wide-spread 
distribution  throughout  the  lower  part  of  the  Yukon  basin  of  rocks 
of  this  same  lithologic  character  that  they  must  have  formed  extensive 
sheets. 

Along  the  eastern  border  of  Norton  Bay  volcanic  rocks  of  a rela- 
tively recent  age  have  been  reported  at  many  places.  Within  the 
region  covered  by  this  report  two  areas  of  vesicular  lavas  have  been 
orally  reported  to  the  writers  by  Mr.  J.  T.  Watkins,  of  the  Coast  and 
Geodetic  Survey.  These  two  areas  are  the  Reindeer  Hills  and  Bes- 
boro  Island.  No  collections  were  made,  but  the  description  of  the 
rocks  clearly  points  to  the  conclusion  that  they  are  both  to  be  included 
within  this  group.  They  probably  mark  a connecting  link  between 
the  well-known  volcanic  flows  of  St.  Michael  on  the  south  and 
of  the  Koyuk  Valley  on  the  north. 

Concerning  the  lavas  along  the  Koyuk,  Mendenhall  says : ° 

The  lava  is  a green,  gray,  or  black  rock,  the  color  depending  in  part  upon 
its  freshness.  It  is  compact  or  vesicular  and  usually  porphyritic,  olivine  being 
the  most  conspicuous  of  the  phenocrysts,  although  plagioclase  is  recognizable 
megascopically  in  some  instances.  Sometimes  the  vesicles  are  filled  with  opal ; 
more  frequently  they  are  without  filling.  The  rock  varies  in  texture,  having 
sometimes  a very  glassy  groundmass  and  in  other  cases  showing  a coarse, 
well-defined,  interstitial  arrangement  with  almost  no  glass.  * * * The 

basalt  beds  have  not  been  disturbed  since  they  were  poured  out.  They  are 
horizontal  wherever  their  attitude  is  determinable  and  overlie  all  the  other 
rocks.  * * * 

Moffit,  who  studied  portions  of  the  large  lava  sheet  occupying  the 
northwestern  corner  of  the  mapped  area,  as  well  as  numerous  other 
flows  in  contiguous  areas  to  the  north,  writes  as  follows  concerning 
these  basalts: b 

In  color  the  lavas  are  dark  gray,  green,  or  nearly  black.  They  are  usually 
very  cellular  or  even  spongy  in  appearance,  but  at  times  compact  and  without 
the  amygdaloidal  cavities.  Outcrops  of  the  older  lavas  in  place  are  not  plenti- 
ful, and  the  edges  of  the  sheets  where  cut  through  by  streams  are  marked 
by  tumbled  heaps  of  blocks  resulting  from  the  jointed  columnar  structure  of 
the  lava.  In  a few  places  they  form  flat-topped  hills  or  mesas  from  20  to  50 
feet  high,  very  conspicuous  when  viewed  from  a distance,  and  evidently  the 
remains  of  partly  eroded  sheets.  Agglomerate  breccias  were  observed  at 
several  points.  A study  of  the  numerous  specimens  collected  shows  them  to 
be  made  up  of  diabase  and  basalts,  both  rich  in  olivine.  In  the  basalts,  espe- 
cially, olivine  phenocrysts  are  abundant  and  very  noticeable  even  in  the  hand 
specimens.  Iddingsite  is  not  infrequent  as  an  alteration  product  of  the  olivine. 

That  a succession  of  outbreaks  of  lava  has  taken  place  is  shown  in  a number 
of  places,  but  probably  most  plainly  in  the  region  about  the  head  of  Kuzitrin 
River,  where  positive  evidence  is  afforded  in  the  terraced  condition  of  the 
different  flows,  three  distinct  benches  occurring  in  one  locality. 

“ Mendenhall,  W.  C.,  op.  cit.,  p.  206. 

b Moffit,  F.  H.,  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska:  Bull.  U.  S.  Geol. 
Survey  No.  247,  1905,  pp.  31,  32-33. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


73 


Observations  made  by  Collier  on  Noxapaga  River  showed  these  more  recent 
lavas  overlying  gravels  which  are  cemented  near  the  contact  by  indurated  clays 
and  contain  pebbles  of  an  older  flow — conclusive  evidence  that  considerable 
time  must  have  elapsed  between  the  first  outbreak  and  the  solidification  of  the 
flows  just  described.  The  source  from  which  the  recent  basalts  of  Noxapaga 
and  Kuzitrin  rivers  were  discharged  lies  to  the  southwest  of  Lake  Imuruk,  this 
being  shown  by  the  scattered  lava  cones  as  well  as  by  the  direction  of  movement 
of  the  flows  themselves. 

On  the  upper  part  of  Ivoyuk  River  a similar  relation  of  basalts  and  gravels 
was  observed  by  Mendenhall.  He  found  on  the  truncated  edges  of  the  schist 
5 feet  of  gravel  made  up  of  schist,  vein  quartz,  and  granite;  this  in  turn  was 
covered  by  an  undisturbed  horizontal  sheet  of  olivine  basalt,  which  has  been 
but  little  affected  by  the  erosive  action  of  the  stream  since  it  came  to  rest  and 
was,  therefore,  believed  by  him  to  be  of  Pleistocene  age. 

During  the  field  season  of  1909  little  detailed  study  of  the  lavas 
was  made,  and  although  the  areal  distribution  of  this  group  of  rocks 
has  been  extended  in  certain  places  the  additions  are  mainly  concern- 
ing details  rather  than  essentials..  It  seems  evident  that  in  the  main 
they  occupy  the  lowlands  of  the  period  in  which  they  were  formed, 
so  that  a thorough  understanding  of  the  distribution  of  the  lavas 
would  indicate  the  former  topography.  It  is  probable  that  more 
extensive  investigations  might  show  that  these  basalts  occupy  a 
greater  area  than  is  shown  on  the  maps.  For  instance,  the  lava  area 
at  the  head  of  the  Mukluktulik  probably  connected  at  one  time  with 
the  lava,  areas  represented  to  the  north  of  the  Koyuk  west  of  Peace 
River,  and  if  the  exposures  were  better  in  the  gently  sloping  spurs 
west  of  Kenwood  Creek  it  is  highly  probable  that  remnants  of  this 
sheet  might  still  be  found  overlying  the  undifferentiated  schists  and 
the  Paleozoic  rocks.  This  patch  of  lava  is  probably  older  than  those 
very  late  effusives  that  overlie  gravel  deposits  of  recent  date,  but,  as 
before  stated,  it  is  believed  that  they  both  belong  to  the  same  general 
geologic  group  and  were  poured  out  on  the  deformed  and  eroded 
surface  of  the  Cretaceous  and  older  rocks. 

Another  small  area  of  recent  effusive  rocks  was  reported  by  Men- 
denhall in  the  hills  near  Grouse  Creek,  a tributary  of  the  Tubutulik. 
It  covers  the  contact  of  the  granites  and  Paleozoic  sediments.  This 
fact  strongly  suggests  that  the  contact,  being  a zone  of  weakness, 
had  been  topographically  a lowland,  in  consequence  of  which  the 
lava  flowed  into  the  depression  and  being  thickest  there  had  remained, 
whereas  the  thinner  parts  had  been  entirely  eroded  away.  There  is 
no  direct  evidence  as  to  the  direction  from  which  this  lava  came,  but 
as  no  near-by  areas  of  similar  rocks  are  known  except  to  the  north 
it  is  assumed  that  this  is  the  direction  from  which  they  flowed, 
although  it  is  realized  that  this  is  little  more  than  a working 
hypothesis. 

On  Bear  River  west  of  Council  a small  area  of  recent  lava  has  been 
reported  and  specimens  of  the  rock  have  been  examined.  It  is  a 


74  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

vesicular  basalt  similar  in  lithologic  character  to  those  from  the 
Koyuk.  There  is  probably  only  a.  small  amount  of  the  rock  present, 
but  little  is  known  of  the  manner  of  occurrence  or  the  areal  relations. 

VEINS. 

Veins  of  different  mineralogical  character  formed  at  different 
times  and  under  different  conditions  have  been  noted  at  many  places. 
They  are  abundant  in  the  areas  of  metamorphic  rocks,  but  are  practi- 
cally absent  in  the  greater  part  of  the  area  occupied  by  the  Cretaceous 
sediments.  Based  on  mineralogical  composition  there  are  two  main 
types  of  vein  filling ; in  one  quartz  predominates,  in  the  other  calcite. 
The  former  are  of  widespread  distribution  and  are  found  in  all  the 
various  kinds  of  rocks;  the  latter  class,  however,  is  almost  entirely 
limited  to  the  immediate  vicinity  of  the  limestone  areas. 

The  veins  in  which  calcite  is  the  main  filling  are  seldom  extensive 
either  horizontally  or  vertically.  They  appear  to  be  formed  usually 
as  the  result  of  shearing  and  infiltration  of  the  calcite  derived  from 
the  adjacent  limestones.  Plate  XII,  B (p.  66) , shows  a portion  of  the 
Paleozoic  limestones  on  the  east  coast  of  Darby  peninsula,  where  an 
intricate  network  of  calcite  veins  forms  a stockwork  through  the 
brecciated  limestones.  Although  the  veins  are  slightly  more  nu- 
merous in  this  view  than  in  the  majority  of  exposures,  the  arrange- 
ment and  general  characters  are  quite  typical.  Plate  VIII,  A 
(p.  46),  already  referred  to,  shows  other  calcite  veins  of  the  same 
general  mode  of  occurrence  near  a greenstone  intrusive.  Some  of 
these  veins  are  undoubted^  younger  than  the  intrusion  of  the  green- 
stones, as  they  cut  them  or  occupy  joint  planes  in  them,  and  it  is 
believed  that  most  of  the  veins  were  produced  either  during  or  subse- 
quent to  the  deformation  of  the  Paleozoic  rocks. 

Calcite  is  practically  the  only  mineral  found  in  the  calcite  veins. 
No  sulphides  or  other  metallic  minerals  have  been  noted  in  them,  and 
they  are  consequently,  in  this  region,  of  no  economic  importance. 

At  least  two  distinct  series  of  quartz  veins  have  been  recognized  in 
the  region;  in  one  the  veins  are  much  contorted  and  sheared,  in  the 
other  crystalline  quartz  with  characteristic  comb  structure  is  found. 
This  difference  in  structure  is  to  be  explained  by  the  difference  in  age 
of  the  two  types.  It  seems  evident  that  to  have  been  crushed,  sheared, 
and  otherwise  deformed  the  veins  must  have  been  in  existence  at  the 
time  of  the  post-Paleozoic  deformation,  whereas  on  the  other  hand 
the  slightly  sheared,  relatively  undisturbed  character  of  the  other 
group  of  quartz  veins  points  to  the  fact  that  they  were  formed  subse- 
quent to  that  period.  Although  these  two  main  groups  have  been 
recognized,  it  is  almost  certain  that  the  older  ones  include  veins 
of  at  least  two  different  ages,  one  earlier  than  the  Silurian  and  one 
later  than  the  Carboniferous,  but  this  point  has  not  been  definitely 


NORTON  BAY-NULATO  REGION,  ALASKA.  75 

settled  and  will  be  difficult  to  prove  owing  to  the  great  amount  of 
post-Paleozoic  deformation. 

So  far  as  can  be  determined  the  content  of  both  classes  of  quartz 
veins  are  nearly  identical.  Sulphide  mineralization  is  usually  absent 
and,  although  a few  copper  or  iron  stains  are  found  at  places,  the 
larger  part  is  formed  of  white  quartz  seldom  even  iron  stained. 
Both  classes  in  places  carry  small  quantities  of  gold.  This  has  been 
determined  mainly  by  chemical  means,  for  the  gold  is  in  the  native 
state  and  is  usually  in  too  small  particles  to  be  recognized  by  the  eye. 
Pieces  of  quartz  from  both  the  older  and  the  younger  quartz  veins, 
however,  have  been  seen  in  which  gold  was  visible.  Assays  from 
different  auriferous  quartz  veins  have  yielded  widely  varying  values, 
but  there  is  no  evident  difference  between  the  quantity  of  gold  car- 
ried in  the  two  groups.  Although  the  gold  content  of  the  older 
and  the  younger  veins  does  not  seem  to  be  materially  different,  the 
fact  that  the  older  ones  are  more  shattered  and  discontinuous  renders 
them  on  the  whole  less  adaptable  to  economic  development  than  the 
younger  veins. 

Few  of  the  contorted  and  sheared  veins  are  more  than  a few  inches 
in  width  and  are  usually  lens-shaped.  Here  and -there,  however,  much 
thicker  lenses  have  been  noted,  and  Mendenhall  calls  attention  a to  a 
conspicuous  example  a few  miles  north  of  Cheenik,  which  is  30  feet 
by  10  feet  by  15  feet.  It  is  described  as  compact  and  barren,  and 
exhibiting  a brilliant  fracture.  Other  large  lenses  were  seen  in  the 
Darby  Range  and  in  the  Bendeleben  Mountains,  but  they  seem  to 
hold  no  promise  of  economically  valuable  minerals.  Mendenhall  also 
notes  a vein  0 feet  wide  striking  north  and  south  in  the  sea  cliff  4 or  5 
miles  from  Rocky  Point,  but  in  this  vein  the  quartz  wTas  rusty,  as 
though  sulphides  were  originally  present  but  had  been  decomposed. 

The  younger  quartz  veins  are  less  sheared  and  shattered  than  the 
older  veins  already  described.  It  should  not  be  concluded,  however, 
from  this  statement  that  they  have  not  been  subjected  to  deformation, 
for  they  are  faulted  and  discontinuous.  Probably  like  the  older  veins 
they  may  belong  to  more  than  one  period  of  formation,  but  evidence 
concerning  this  point  is  not  conclusive.  The  terms  “ younger  ” and 
“ older  ” quartz  veins  are  therefore  to  be  regarded  as  purely  relative, 
though  in  a broad  way  the  former  are  pre-Paleozoic,  whereas  the  latter 
are  post-Paleozoic.  Some  of  the  younger  quartz  veins  cut  the  pre- 
Cretaceous  granites  so  that  a clue  to  their  age  is  afforded.  No  quartz 
veins  have  been  found  in  the  more  recent  olivine  basalts,  and  thus  the 
upper  limit  of  their  age  is  determined. 

Like  the  older  veins  the  more  recent  quartz  veins  are  usually  nar- 
row and  seldom  can  be  traced  for  long  distances.  They  are  particu- 


“ Mendenhall,  W.  C.,  op.  cit.,  p.  211. 


76 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


larly  numerous  in  the  black  quartzites  and  slates  of  the  Paleozoic 
rocks  and  in  that  relation  form  an  intricate  network  of  veinlets,  many 
of  which  are  only  a fraction  of  an  inch  in  width.  Sulphides,  although 
on  the  whole  relatively  unimportant  even  in  the  later  veins,  are  more 
abundant  than  in  the  older  group.  They  are  usually  iron  and  copper 
pyrite,  but  galena,  arsenopyrite,  and  stibnite  are  found.  The  latter 
minerals,  however,  where  found  in  considerable  quantities,  as  at 
Omilak  and  Bluff,  are  not  associated  with  quartz  veins  but  seem  to  fill 
fractures  in  the  country  rock. 

Considering  the  inetamorphic  area  as  a whole,  it  may  be  stated 
that  the  mineralization  is  widespread,  but  that  the  veins  are  seldom 
individually  continuous.  The  mineralization  is  more  in  the  form  of 
a stockwork  or  mineralized  zone  than  in  sharply  defined  single  veins. 
Owing  to  this  disseminated  character  of  mineralization  the  localiza- 
tion of  ore  bodies  is  not  pronounced,  and  it  is  believed  that,  if  com- 
mercially valuable  deposits  are  found,  they  will  be  more  or  less  simi- 
lar to  the  Juneau  type  of  deposits. 

Further  consideration  of  the  veins  which  have  been  prospected  will 
be  given  in  a later  part  of  this  report  dealing  with  the  economic 
geology  of  the  region  (pp.  127-136). 

UNCONSOLIDATED  DEPOSITS. 

Unconsolidated  deposits  occur  throughout  the  Nulato-Council 
region  and  are  important  because  some  of  them  contain  economically 
valuable  minerals.  In  the  following  section  the  distribution  and 
general  characters  of  the  different  types  will  be  described,  the  eco- 
nomic features  being  left  for  separate  treatment  in  the  later  chapter 
on  the  economic  geology  of  the  region.  For  this  reason  specific 
description  of  the  different  creek  gravels  will  be  omitted  here  and 
the  main  attention  will  be  directed  to  the  more  general  features  of 
these  deposits. 

Broadly  considered,  the  unconsolidated  deposits  may  be  divided 
into  two  classes;  in  one  class  the  material  is  practically  unsorted, 
whereas  in  the  other  the  material  has  been  transported,  mainly  by 
water,  and  deposited  at  some  distance  from  the  place  where  the  waste 
originated.  To  the  first  class  belong  the  talus  of  frost-riven  material 
and  hillside  waste  covering  the  surface  of  most  of  the  upland  region ; 
to  the  second  class  belong  the  gravels  of  various  origins  and  also, 
for  the  purposes  of  this  paper,  the  glacial  deposits.  There  are  grada- 
tional phases  between  the  two  classes,  but  the  main  difference  on 
which  emphasis  is  placed  is  that  the  latter  are  in  the  main  water 
sorted,  whereas  the  former  are  not. 

UNSORTED  DEPOSITS. 

As  has  already  been  stated,  the  main  characteristic  of  this  group 
of  deposits  is  that  they  have  been  little,  if  at  all,  affected  by  running 


NORTON  BAY-NULATO  REGION,  ALASKA.  77 

water.  Some  sorting  has,  of  course,  been  effected  by  the  gravitative, 
downhill  creep  of  the  material,  but  this  is  relatively  unimportant. 
These  deposits  are,  therefore,  normally  made  up  of  angular  material 
derived  from  the  ledges  directly  up  the  slope  from  the  place  where 
they  are  formed,  or  they  are  the  frost-shattered  fragments  of  the 
country  rock  immediately  beneath  the  surface. 

Deposits  of  this  sort  are  particularly  characteristic  of  the  uplands, 
where  the  strong  temperature  changes  allow  rapid  disintegration  of 
the  underlying  rock.  Plate  XI,  B (p.  58),  shows  a typical  view  of 
this  sort  of  deposit  in  the  granite  area  north  of  the  Kwiniuk,  and 
might  be  duplicated  by  pictures  from  all  parts  of  the  field.  Of  course 
the  waste  is  not  always  as  coarse  as  is  shoAvn  in  this  view,  for  the  size 
of  the  fragments  depends  upon  the  physical  features  of  the  rocks 
from  which  the  material  was  derived.  Therefore,  in  the  sandstone 
shale  regions  the  float  is  in  smaller  pieces  than  in  the  places  where 
the  bedrock  is  granite. 

When  the  disintegration  takes  place  on  a hillside,  as  shown  in  the 
plate  (XI,  B ),  instead  of  on  top  of  a hill,  the  waste  as  it  is  formed 
spreads  down  the  slope  and  forms  a mantle  of  rock  fragments  similar 
to  that  shown  on  the  hillsides  across  the  valley  in  Plate  III,  A (p.  22) . 
The  foreground  of  this  view  shows  the  general  character  of  this 
waste  sheet  on  the  near  side  of  the  valley.  Waste  sheets  of  this  sort 
are  usually  coarser  and  thinner  toward  the  ridge  and  become  grad- 
ually finer  and  thicker  toward  the  valley  floor. 

The  deposits  of  unsorted  rock  waste  are  so  universal  that  if  they 
were  shown  on  the  geologic  map  they  would  obscure  all  the  other 
patterns;  hence  they  have  not  been  represented.  This  course  is  fur- 
ther justified  by  the  fact  that  they  have  no  economic  value  and  are 
therefore  unimportant  to  the  present  study.  If,  then,  the  reader 
desires  to  reproduce  the  surface  features  of  the  Nulato-Council  region 
precisely  it  would  be  necessary  to  imagine  practically  all  of  the  area 
not  occupied  by  gravels  as  covered  by  the  unsorted  deposits,  except 
here  and  there  where  bedrock  outcrops.  Such  ledges,  however,  prob- 
ably do  not  form  one  per  cent  of  the  entire  area. 

DEPOSITS  OF  TRANSPORTED  MATERIAL. 

The  deposits  of  transported  material  may  be  divided  into  marine 
deposits,  nonmarine  water-laid  deposits,  and  glacial  deposits.  Typ- 
ical examples  of  each  of  these  three  classes  have  been  recognized 
in  the  field,  but  the  gradations  between  the  different  classes  and 
the  absence  of  detailed  investigations  prevent  the  separation  of 
the  three  groups  on  the  map.  The  marine  and  the  nonmarine 
water-laid  deposits  show  examples  of  deposits  formed  at  more  than 
one  time,  so  that  these  two  are  further  divisible  into  older  and 


78 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


younger  gravels.  The  glacial  deposits  have  not  been  so  thoroughly 
studied  as  the  others  and  only  one  division  has  been  recognized.  It 
is  by  no  means  improbable  that  with  further  investigation  these  de- 
posits also  might  be  subdivided.  It  should  be  noted  that  the  terms 
“ older  ” and  “ younger  ” refer  to  the  relative  age  within  the  group 
and  that  it  by  no  means  follows  that  one  of  the  older  marine  deposits 
is  equivalent  in  time  of  formation  to  a particular  example  of  an  older 
deposit  of  nonmarine  water-laid  gravels.  Such  refined  correlations 
must  await  future  investigation.  Broadly  speaking,  however,  the 
group  of  older  marine  sediments  are  equivalent  in  age  to  the  group 
of  older  nonmarine  water-laid  deposits. 

MARINE  GRAVELS. 

Lithologically  the  younger  marine  gravels  present  great  diversity 
depending  in  large  measure  upon  the  material  of  which  the  shore 
line  is  composed.  The  topography  also  exercises  a considerable  in- 
fluence on  the  physical  characters,  for  in  the  bights  between  head- 
lands the  materials  are  fine-grained,  whereas  near  the  promontories 
bowlders  and  coarse  gravels  predominate.  Near  the  mouths  of  the 
larger  streams  the  mixture  of  fluviatile  and  marine  deposits  is  so  com- 
plex that  it  is  impossible  to  separate  the  two.  On  the  present  shore 
line  from  the  mouth  of  the  Koyuk  to  Cheenik  the  marine  gravels 
present  a great  diversity,  ranging  from  fine  muds  to  bowlders  10  feet 
or  more  in  diameter.  Here  and  there  sea  stacks  interrupt  the  con- 
tinuity of  the  gravels  so  that  the  floor  on  which  the  present  deposition 
is  taking  place  is  irregular.  In  the  sheltered  stretches  of  the  coast 
enormous  quantities  of  drift  wood,  probably  brought  down  by  the 
Yukon,  are  accumulating  and  are  being  buried  as  part  of  the  marine 
deposits.  Marine  shells,  except  near  the  mouth  of  the  larger  streams, 
are  not  abundant  in  the  deposits  being  formed  at  the  present  time. 
Garnet  and  magnetite  sand  so  common  along  the  beach  from  Topkok 
westward  is  almost  entirely  absent  in  the  eastern  part  of  the  coast  line. 

Marine  deposits  now  somewhat  elevated  above  the  position  in  which 
they  were  laid  down  and  consequently  belonging  to  the  class  of  older 
gravels  have  been  found  at  many  places.  These  deposits  are  perhaps 
best  shown  by  the  coastal  plain  east  of  Norton  Bay  north  of  the 
Reindeer  Hills.  Few  sections  of  these  gravels  have  been  made,  so 
that  their  depth  and  character  are  not  well  known.  A prospect  hole 
near  the  mouth  of  the  Ungalik  was  sunk  nearly  100  feet  without 
reaching  bed  rock.  The  fact,  however,  that  bed  rock  outcrops  at 
Island  Point  only  a few  miles  away  shows  that  the  floor  on  which 
these  sediments  have  been  deposited  is  uneven. 

On  the  east  coast  of  Darby  Peninsula  old  sea  caves  20  to  30  feet 
above  present  sea  level  were  recognized  at  a number  of  places  and  are 
shown  in  Plates  III,  B (p.  22) , and  XIII,  B (p.  66) , already  described. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


79 


Mendenhall  also  observed  evidence  of  former  higher  stands  of  the 
sea,  for  he  says,®  “ On  the  west  shore  of  Golofnin  Bay  raised  gravels 
were  observed  capping  the  schistose  bluffs  at  Rocky  Point.  From 
this  point  westward  evidence  of  uplift  is  increasingly  abundant  and 
consists  of  terraces,  high  gravels,  and  superposed  streams.”  From 
this  evidence  it  follows  that  at  a time  not  remote  geologically  the  sea 
stood  in  places  at  least  25  feet  above  its  present  position,  so  that  con- 
siderable areas  now  dry  land  were  formerly  covered  by  the  sea.  There- 
fore marine  gravels  are  to  be  expected  inland  from  the  present  shore 
and  have  been  recognized  at  many  places.  Some  of  these  deposits 
have,  however,  been  subsequently  reworked  by  the  streams,  so  that 
their  marine  characters  have  been  obliterated.  There  is  but  little 
question  that  parts  of  the  gravel  deposits  at  the  head  of  Golofnin 
Bay  and  in  the  bight  between  the  Miniatulik  and  Isaacs  Point  are  of 
marine  origin,  but  the  transition  between  the  evident  marine  material 
and  the  equally  evident  fluviatile  gravels  is  so  gradual  that  no  line 
of  separation  can  be  drawn  without  numerous  sections  not  now 
available. 

Not  only  are  there  evidences  of  former  higher  levels  of  the  sea,  but 
at  Bluff  a beach  line  is  developed  several  feet  below  the  present  sea 
level  so  that  at  an  earlier  time  the  marine  gravels  did  not  extend  in- 
land so  far  as  they  now  do.  This  emphasizes  the  point  that  the 
various  members  of  the  unconsolidated  marine  deposits  are  not  of  the 
same  age,  but  that  the  sea  level  has  oscillated  considerably  during  a 
long  period. 

RIVER  GRAVELS. 

Every  stream  in  the  region  is  forming  gravel  deposits  and  examples 
of  this  class  are  abundantly  represented.  Owing  to  the  scale  of  the 
map,  however,  only  the  larger  deposits  have  been  shown,  so  that  in 
reading  the  map  this  fact  should  be  constantly  borne  in  mind  and  it 
should  also  be  remembered  that  even  in  the  headwater  branches  of 
the  smallest  streams  water-transported  gravels  are  found.  As  has 
already  been  pointed  out  the  creek  gravels  may  be  divided  into  an 
older  and  a younger  group.  These  two  may  so  grade  into  each  other 
that  no  sharp  line  of  demarcation  can  be  drawn.  In  this  report, 
however,  the  lower  bench  gravels  up  to  10  or  20  feet  above  the  stream 
are  considered  as  belonging  to  the  younger  group. 

The  lithologic  character  of  the  stream  gravels  depends  very  largely 
on  the  kind  of  rocks  exposed  in  the  valley  in  which  they  occur.  Thus 
in  the  case  of  a small  stream  flowing  in  a valley  carved  in  only  one 
kind  of  rock  the  pebbles  are  entirely  of  this  kind  of  rock,  whereas  in 
the  case  of  the  larger  streams,  such,  for  instance,  as  the  Yukon,  the 


ff  Mendenhall,  W.  C.,  op.  cit.,  p.  210. 


80 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


gravels  have  been  derived  from  a great  variety  of  different  rocks 
outcropping  within  the  basin  and  show  a great  diversity  of  lithologic 
character.  So  far  as  has  been  determined  almost  all  of  the  younger 
stream  gravels  are  of  local  origin;  that  is,  have  been  formed  in  the 
valleys  in  which  they  now  occur.  This  point,  however,  requires  con- 
siderable additional  study,  for  similarity  of  rock  types  and  the  large 
area  covered  are  likely  to  give  an  appearance  of  simplicity  not  justi- 
fied by  more  searching  examination.  An  exception  to  this  rule  is 
afforded  by  the  gravels  of  Melsing  Creek,  where  granite  bowlders 
derived  from  the  Bendeleben  Mountains  are  intimately  associated 
with  gravels  of  distinctly  local  origin. 

On  the  smaller  streams  the  thickness  of  the  gravel  is  only  a few 
feet,  but  on  the  larger  streams,  especially  those  that  have  undergone 
a complex  geologic  history,  the  gravels  may  be  more  than  100  feet 
thick.  These  deeper  gravels  undoubtedly  belong,  in  part,  to  the 
older  ones,  but  as  they  grade  directly  into  the  present  creek  gravels 
differentiation  can  not  be  made  here,  and  they  will  be  described  at 
this  place.  On  Mystery  Creek,  midway  between  its  junction  with  the 
Niukluk  and  the  point  where  it  leaves  the  hills,  a shaft  penetrated 
gravels  to  a depth  of  102  feet.  The  gravels  were  but  slightly  water- 
worn  and  contained  small  shells  in  a perfect  state  of  preservation. 
Bearing  on  this  same  question  is  the  fact  that  in  1906  a hole  was  sunk 
midway  between  Bear  and  Fox  Creeks  west  of  Council  in  a bench 
deposit  about  50  feet  above  the  river.  This  drill  hole  reached  a 
depth  of  250  feet,  all  this  distance  being  in  gravel.  Such  a depth 
would  make  the  bottom  of  the  hole  at  least  50  feet  below  sea  level.  As 
bedrock  outcrops  within  2 to  3 miles  of  this  place,  this  thick  deposit 
of  gravels  strongly  suggests  the  probability  of  having  been  formed 
by  an  earlier  stream  which  carved  its  channel  when  the  land  stood 
relatively  higher  with  respect  to  the  sea  than  it  does  now. 

Another  deep  gravel  deposit  has  been  located  in  the  hills  west  of 
the  Koyuk  near  camp  B16.  At  this  place  a shaft  192  feet  deep  was 
sunk  all  the  way  through  well-rounded  gravels.  The  bottom  of  the 
deposit  is  a considerable  distance  below  sea  level  and  points  to  a 
change  in  respect  to  sea  level  since  the  channel  was  carved.  This 
channel  was  probably  due  to  the  effusion  of  some  of  the  post-Creta- 
ceous lavas  which  obstructed  a former  stream  course,  but  the  fact 
that  the  bottom  of  the  channel  is  far  below  sea  level  can  be  explained 
only  by  assuming  that  since  it  was  formed  the  region  has  been  rela- 
tively depressed.  A further  description  of  this  deposit  is  given  on 
pages  110-113. 

Although  practically  nothing  is  known  of  the  depth  of  bedrock 
in  the  bottom  of  the  Yukon  Valley,  there  are  many  things  which 
lead  to  the  conclusion  that  the  gravel  filling  may  in  places  be  very 
thick.  This  is  also  true  of  the  Koyukuk  and  of  the  lower  parts  of  the 


NORTON  BAY-NULATO  REGION,  ALASKA. 


81 


Kateel,  the  Gisasa,  and  other  large  tributaries.  It  is  possible  that 
these  deeper  gravels  are  not  solely  of  fluviatile  origin,  but  data  are  too 
few  to  permit  a final  analysis  of  the  problem. 

In  addition  to  the  gravels  known  to  belong  to  an  older  group,  be- 
cause they  underlie  the  present  stream  gravels,  there  are  also  older 
gravels  whose  age  is  determined  by  the  fact  that  the  stream  has  cut 
its  valley  down  into  them.  In  other  words,  there  are  bench  deposits 
which  mark  either  a relative  uplift  of  the  land  or  a change  in  the 
erosive  power  of  the  streams  in  the  recent  past.  In  elevation  above 
the  adjacent  streams  the  benches  range  from  only  a few  feet  to 
several  score  feet,  the  higher,  of  course,  being  more  obliterated  by 
having  been  exposed  to  erosin  a longer  time  than  the  lower. 

Russell,®  who  ascended  the  Yukon  in  1890,  called  attention  to  cer- 
tain obscure  indications  of  terraces  or  sea  cliffs  at  an  elevation  of 
1,500  or  2,000  feet  on  a number  of  the  hills  below  Nulato.  In  tra- 
versing these  ridges  in  1909  the  party  found  no  traces  of  gravel  at 
such  high  elevations,  and  it  is  believed  that  the  appearance  of  nearly 
horizontal  benches  is  due  to  the  beveling  of  the  stratified  rocks  of  the 
Cretaceous,  which  outcrop  in  these  hills.  Lower  down,  however,  at 
an  elevation  of  about  50  feet  above  the  river,  silts  and  sands  form  pro- 
nounced benches.  Although  these  deposits  have  not  been  studied  in 
detail,  their  position  and  topographic  expression  suggest  that  they 
mark  former  river-laid  gravels  and  sands  subsequently  dissected  by 
the  relative  doAvn  cutting  of  the  present  river. 

Bench  gravels  are  found  in  the  Shaktolik  Yalley  and  were  espe- 
cially noted  near  camp  A10,  where  a broadly  open  older  valley  floor 
covered  with  gravels  has  been  dissected  by  the  narrow  rock-walled 
canyon  of  the  present  stream.  Much  of  this  bench  gravel  is  heavily 
iron  stained.  This  feature  was  also  noted  at  several  places  farther 
downstream  near  camp  A13.  From  the  topographic  similarity  it  is 
probable  that  bench  deposits  corresponding  to  those  noted  on  the 
Shaktolik  occur  also  in  the  Gisasa  and  Kateel  valleys,  but  they  were 
not  searched  for. 

In  southeastern  Seward  Peninsula  bench  gravels  are  by  no  means 
uncommon  along  the  lower  slopes  of  many  of  the  valleys.  The  deep 
holes  on  Alameda  Creek  and  on  the  Niukluk  were  started  to  explore 
some  of  these  bench  deposits  and  part  of  the  other  gravels  belonging 
to  this  class,  but  as  they  grade  insensibly  into  the  lower  gravels  they 
have  been  described  with  the  older  ones.  There  are,  however,  many 
places,  as,  for  instance,  along  Ophir  Creek,  in  the  Council  region, 
where  bench  gravels  only  a few  feet  thick  have  been,  found.  Some 
of  these  are  auriferous  and  some  are  not. 

a Russell,  I.  C.,  Notes  on  the  surface  geology  of  Alaska  : Bull.  Geol.  Soc.  America,  vol. 
1,  p.  139. 

71469°— Bull.  449—11 6 


82 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


The  geologic  significance  of  the  finding  of  bench  deposits  at  differ- 
ent elevations  widely  distributed  throughout  the  entire  Nulato- 
Council  region  is  that  there  have  been  frequent  oscillations  of  the 
streams  with  respect  to  sea  level.  These  oscillations  may  have  been 
due  in  part  to  climatic  changes,  but  in  part  they  are  to  be  accounted 
for  only  by  assuming  movements  of  the  land  with  respect  to  the  sea. 
Although  the  presence  of  benches  above  the  streams  at  the  present 
time  shows  that  there  has  been  an  uplift  of  the  land,  the  fact  that 
some  of  the  larger  streams  have  their  rock-cut  floors  below  sea  level 
shows  that  the  sum  of  the  recent  upward  movements  indicated  is  not 
at  present  equal  to  the  sum  of  the  downward  movements  in  the 
recent  past. 

A peculiar  type  of  gravel  deposit,  in  part  fluviatile  in  origin,  but 
probably  also  produced  by  other  agencies,  is  found  in  the  basin  low- 
lands, such  as  Death  Valley  and  the  Fish  River  lowland  north  of 
the  gorge.  Sections  in  these  basins  have  not  been  made,  and  little 
can  be  determined  from  the  examination  of  their  surficial  aspects. 
Mendenhall  states  a that  the  Fish  River  lowland  is  filled  with  deposits, 
“ coarse  near  the  borders  and  fine  near  the  center  of  the  basin.  The 
depth  of  this  filling  is  purely  conjectural,  but  presumably  is  not  great. 
No  islands  of  bedrock  exist  within  it,  as  far  as  known,  but  sand  and 
gravel  prominences,  rising  in  some  instances  30  or  40  feet  above  the 
general  level,  are  abundant  over  it,  and  are  interpreted  as  remnants 
of  a slightly  higher  level  generally  destroyed  by  the  meanderings  of 
the  stream.”  Brooks  b attributed  the  origin  of  these  basins  to  warp- 
ings  of  the  crust,  whereby  depressions  were  formed,  which  have  been 
subsequently  filled.  So  long  as  the  topography  of  the  floor  on  which 
the  gravels  rest  has  not  been  determined,  it  seems  unsafe  to  attempt 
an  explanation  of  their  origin.  The  fact,  however,  that  the  uplands 
are  so  abruptly  cut  off  by  the  lowland  suggests  that  the  basin  is 
mainly  due  to  erosion  rather  than  to  deformation.  The  question  of 
the  origin  of  the  basin  is  not  important  in  this  discussion,  for  under 
either  view  the  flats  are  believed  to  have  been  formed  by  the  filling 
of  a depression  either  by  fluviatile  or  lacustrine  deposits. 

Owing  to  the  high  northern  latitude,  many  of  the  deposits  are 
permanently  frozen,  and  as  the  presence  or  absence  of  frost  in  the 
ground  has  an  important  effect  upon  mining  enterprises  a general 
statement  of  the  distribution  of  the  ground  ice  may  be  made.  Gen- 
erally the  older  gravels  are  permanently  frozen  and  some  of  the 
bench  deposits  contain  beds  of  clear  ice  in  places  a score  or  more  feet 
thick.  So  far  as  is  known,  the  presence  or  absence  of  trees'  on  the 
gravels  is  no  sure  indication  that  the  ground  is  thawed,  for  many 

a Mendenhall,  op.  cit.,  p.  207. 

b Brooks,  A.  H.,  The  geography  and  geology  of  Alaska  : Prof.  Paper  U.  S.  Geol.  Survey 
No.  45,  1906,  p.  282. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


83 


instances  are  known  of  trees  of  large  size  growing  on  frozen  ground. 
For  instance,  at  Nulato,  as  Russell  a states,  a well  25  feet  deep  went 
through  clay  and  sand  beds,  which  were  frozen  solid  with  the  excep- 
tion of  certain  dry  sandy  layers,  and  yet  spruce  was  abundant  in  the 
neighborhood  before  it  was  cut  off.  Although  most  of  the  older  gravel 
deposits  are  frozen,  those  near  the  present  streams  are  usually 
thawed.  Whether  this  condition  is  due  to  the  better  drainage  of  the 
present  stream  gravels  which  prevents  the  formation  of  ice  is  not 
known.  There  is  a strong  suggestion,  however,  that  the  frozen  condi- 
tion is  due  to  past  climatic  controls  and  is  in  a way  an  inheritance 
rather  than  a process  now  in  progress.  This  possibility  receives  some 
support  from  the  distribution  of  ground  ice  in  the  marine  gravels. 
In  the  present  beach  deposits  permanent  frost  is  unknown,  whereas 
in  the  older  ones  it  is  almost  universally  present. 

GLACIAL  DEPOSITS. 

Glacial  deposits  are  limited  to  the  mountain  regions,  and  there  is 
strong  reason  for  believing  that  the  Nulato- Council  region  has  not 
been  covered  by  a large  ice  sheet  in  sufficiently  recent  time  to  have 
had  any  effect  on  the  general  topography  or  on  the  unconsolidated 
deposits.  Near  the  Bendeleben  and  Darby  highlands,  however,  there 
are  indisputable  evidences  of  former  valley  glaciers  of  the  alpine 
type.  Deposits  formed  by  this  agency  are  of  three  kinds — in  one 
the  materials  are  unsorted  and  are  dumped  in  irregular  heaps  essen- 
tially as  they  were  deposited  when  the  ice  melted  away;  in  another 
the  glaciers  obstructed  the  normal  drainage  and  thus  formed  lakes 
on  which  ice-rafted  bowlders  were  transported  and  deposited ; in  the 
third  the  morainic  material  was  transported  away  from  the  melting 
ice  by  water  and  so*  although  originating  through  glacial  action,  the 
present  form  of  the  deposits  is  characteristic  of  stream  deposition. 

A particularly  clear  example  of  the  unsorted  morainic  material 
has  been  reported  by  Hensliaw  in  the  Fargon  River  valley.  At 
the  edge  of  the  mountains  where  the  stream  debouches  into  the  Fish 
River  lowland  a long  spur  on  the  east  side  of  the  valley  marks  the 
margin  of  a former  glacier.  West  of  this  stream,  near  the  same  place, 
the  low  divide  between  the  Fargon  and  Ophir  Creek  is  also  formed 
of  morainic  material,  with  small  kettle  holes  or  depressions  irregu- 
larly distributed  over  its  surface.  Farther  up  Fargon  River  a 
moraine  from  McKelvie  Creek  extends  out  into  the  main  valley  and 
shows  characteristic  morainic  topography.  This  same  condition  is 
also  true  of  Helen,  Decatur,  and  many  of  the  other  tributary  creeks. 
The  absence  of  frontal  moraines  marking  the  recessional  stages  of 
the  main  glacier  is  probably  to  be  explained  by  assuming  that  the 


Russell,  I.  C.,  op.  cit.,  p.  129. 


84 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


material  was  washed  away  by  the  water  from  the  melting  ice  and  not 
allowed  to  accumulate.  According  to  this  interpretation,  part  of  the 
gravels  of  the  Fish  River  lowland  and  of  Pargon  River  are  of 
glacio-fluviatile  origin.  The  presence  of  granite  bowlders  in  the 
gravels  of  Melsing  Creek  is  probably  due  to  this  period  of  glacio- 
fluviatile  activity  when  the  ice  stood  sufficiently  far  south  to  allow 
a discharge  from  its  front  across  the  low  divide  at  the  head  of  Mel- 
sing and  Ready  Bullion  creeks. 

In  the  upper  Niukluk  Valley,  near  Mount  Bendeleben,  glacial  de- 
posits were  observed,  in  1908,  on  both  the  north  and  the  south  sides 
of  the  range.  Moraines  are  also  reported  on  Baker  Creek  and  Oregon 
Creek,  so  that  glacial  phenomena  are  observable  throughout  the 
Bendeleben  Mountains ; but  the  consensus  of  opinion  by  all  observers 
is  that  these  glaciers  were  never  very  extensive. 

Around  the  higher  parts  of  the  Darby  Range  there  are  also  strong 
evidences  of  local  glaciation  in  the  past.  Marginal  moraines,  however, 
have  not  been  recognized  beyond  the  front  of  the  hills  and  it  is  prob- 
able that  they  were  not  deposited.  Whether  their  absence  means  that 
they  were  not  allowed  to  accumulate  because  of  the  rapid  removal  of 
debris  by  the  water  flowing  from  the  front  of  the  glaciers  or  whether 
the  ice  did  not  extend  beyond  the  front  of  the  mountains  has  not  been 
determined. 

Near  camp  C13,  where  the  branch  of  the  Etchepuk  makes  an  abrupt 
angular  turn  from  a southwest  to  a northwest  course,  there  is  abun- 
dant evidence  of  a morainic  ridge  which  is  probably  responsible  in 
part  for  the  sharp  bend  in  the  stream.  Although  there  is  no  clear 
proof  of  the  conclusion,  it  is  believed  that  at  one  time  there  may  have 
been  a discharge  of  this  branch  by  way  of  the  Kwiniuk  basin.  Al- 
though the  evidence  is  conflicting,  there  is  a possibility  thaf  the  Fish 
River  lowland  also  may  be  due  to  glaciation,  but  this  interpretation 
requires  much  more  detailed  investigation  and  is  advanced  with  many 
reservations. 

That  glaciation  has- considerably  modified  the  topography  within 
parts  of  the  Darby  Range  by  the  deposits  of  glacio-fluviatile  mate- 
rial is  well  shown  by  the  ridges  south  of  camp  Cll,  which  form  part 
of  the  Etchepuk  divide.  These  ridges  are  mainly  due  to  the  work 
of  glaciers  that  occupied  the  valleys  on  either  side,  but  the  presence 
of  water-worn  cobbles  intimately  associated  with  angular  ice-trans- 
ported debris  shows  that  both  agencies  were  operative  in  the  deposi- 
tion of  the  material.  From  the  topography  it  seems  probable  that 
this  morainic  deposit  accumulated,  as  is  indicated  in  fig.  7,  where 
the  tongues  of  ice  are  represented  by  CC,  with  nunataks,  or  islands 
of  the  underlying  rocks  (AA),  separated  by  low  saddles  now  filled 
with  moraines  (BB).  The  eleyation  of  the  top  of  the  morainic 
material  above  the  floor  of  the  present  stream  is  about  400  feet.  East 


NORTON  BAY-NULATO  REGION,  ALASKA. 


85 


of  this  point  and  farther  up  the  ridge  there  is  no  -evidence  of  glacial 
deposits,  and  bare  rock  ledges  outcrop. 

All  of  these  examples  of  glaciation  have  been  taken  from  the  west 
side  of  the  range,  the  one  to  which  the  main  attention  of  the  party 
of  1909  was  paid.  Apparently  glaciation  is  more  notable  on  this 
side  than  on  the  eastern,  for  Mendenhall  says:  a “ Many  of  the  higher 
areas  have  not  been  examined  in  detail  and  it  is  possible  that  small 
local  glaciers  may  have  existed  in  the  heads  of  some  of  the  valleys, 
but  no  evidence  of  their  existence  was  gathered  during  the  summer, 
and  views  into  the  mountains  from 
levels  but  little  below  their  highest 
points  revealed  no  forms  suggestive  of 
ice  work.” 

AGE  OF  UNCONSOLIDATED  DEPOSITS. 

A consideration  of  the  unconsolidated 
deposits  as  a whole  indicates  a great 
diversity  of  age,  represented  by  the  dif- 
ferent types.  It  is  not  possible  as  yet 
to  correlate  these  various  deposits  defi- 
nitely, but  in  a broad  way  they  are  more 
or  less  closely  related;  the  larger  part 
are  Quaternary,  but  probably  none  are 
older  than  the  upper  Tertiary.  From 
that  as  the  maximum  age  they  grade 
down  to  the  present  day  as  the  mini- 
mum. Assuming  that  the  period  of  maximum  glaciation  was  practi- 
cally contemporaneous  in  the  northern  hemisphere,  the  glacial 
deposits  already  noted  may  be  regarded  as  Pleistocene.  Certain 
bench  deposits  contain  mastodon  and  mammoth  bones,  wdiich  show 
that  they,  too,  may  have  been  deposited  during  Pleistocene  time. 
Gravels  containing  bones  of  this  age  have  been  reported  in  the  Buck- 
land  Valley,  near  Candle,  on  Ophir  Creek,  and  along  the  Inglutalik, 
where  they  are  numerous. 

From  the  accounts  of  Henshaw,  the  well-recognized  moraine,  at  the 
point  where  the  Pargon  River  leaves  the  hills,  has  been  deposited  on 
top  of  the  gravels  of  the  Fish  River  lowland.  Whether  this  means 
that  all  these  gravels  are  older  than  the  glaciation  or  whether  the 
recognized  moraine  may  only  be  one  of  the  recessional  stands  of  the 
ice  after  a much  farther  southward  advance  has  not  been  determined, 
so  that  no  statement  of  the  age  of  the  two  types  of  gravel  can  be 
made.  From  the  meager  evidence,  however,  it  seems  probable  that 
these  gravel-plain  deposits  are  in  part  contemporaneous  with  the 


Figure  7. — Diagram  showing  rela- 
tions of  glacial  material  on 
Etchepuk  divide.  (A,  Rocky 
knobs.  B,  marginal  glacial  de- 
posits. C,  Valley  glaciers.) 


° Mendenhall,  W.  C.,  op.  cit.,  p.  208. 


86 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


glacial  deposits  and  in  part  older  than  the  period  when  the  ice  stood 
at  the  point  where  Pargon  River  leaves  the  hills. 

Concerning  the  age  of  the  marine  gravels  there  is  considerable  un- 
certainty. Direct  observations  in  this  actual  area  reveal  no  evidence, 
but  from  analogy  with  better-known  parts  of  the  peninsula  there 
are  grounds  for  regarding  them  in  part,  at  least,  as  late  Tertiary. 
The  evidence  bearing  on  this  point  is  as  follows : In  the  coastal  plain 
near  Nome,  which  topographically  resembles  the  coastal  plain  east 
of  Norton  Bay,  fossils  which,  according  to  Dali,  are  of  Tertiary  age 
have  been  found;  furthermore,  glacially  striated  rocks  at  Nome  in 
the  upper  part  of  the  deposit  indicate  that  this  part  was  contem- 
poraneous with  the  period  of  glaciation.  In  other  words,  the  lower 
part  of  the  coastal-plain  deposits  may  be  Tertiary  and  the  upper  part 
Pleistocene,  and  perhaps  still  more  recent  gravels  rest  on  top,  depos- 
ited as  the  former  sea  bottom  emerged  from  the  water  and  took  on 
its  present  relation  to  sea  level.  As  has  been  already  pointed  out, 
however,  a long  time  is  required  for  the  various  oscillations  of  the 
coast,  so  that  the  marine  deposits  have  a considerable  range  in  age. 

STRUCTURAL  GEOLOGY. 

From  the  foregoing  description  of  the  various  rocks  in  the  Nulato- 
Council  region  it  is  evident  that  the  structures  they  present  are  com- 
plex. Already  the  facts  have  been  brought  out  that  there  are  a group 
of  metamorphic  rocks  which  were  dynamically  deformed  before  the 
laying  down  of  the  Cretaceous  sediments,  that  the  Cretaceous  rocks 
have  themselves  been  folded  and  deformed,  and  that,  latest  of  all, 
there  have  been  undeformed  lava  flows  and  gravel  deposits.  It  is 
thus  evident  that  at  least  two  periods  of  mountain  building  and 
deformation  have  affected  the  older  rocks,  and  that  their  present 
distribution  and  characters  are  the  resultants  of  these  perhaps  op- 
posed actions.  These  actions  have  produced  enormous  dislocation 
and  folding,  which  can  only  be  vaguely  realized  and  which  can  not 
be  represented  in  section  except  so  diagrammqtically  as  to  obscure 
the  facts.  Furthermore,  precise  details  of  complex  structure  can  not 
be  gained  on  an  exploratory  survey.  It  has  seemed  best,  therefore, 
not  to  draw  cross  sections  with  the  appearance  of  finality,  but  rather 
to  call  attention  to  the  geologic  maps  (Pis.  V and  VI,  in  pocket), 
from  which  sections  may  be  constructed.  In  this  way  the  hypothet- 
ical condition  will  be  more  clearly  discriminated  from  the  actual  facts. 

The  large  scale  structural  features  of  the  region  are  folds  and 
faults.  Many  examples  of  each  were  observed  in  the  field,  and  many 
others  must  be  assumed  in  order  to  explain  the  areal  distribution  of 
the  various  rock  groups.  In  the  areas  of  metamorphic  rocks  the 


NORTON  BAY-NULATO  REGION,  ALASKA. 


87 


structure  seemed  to  be  simple  in  places  where  outcrops  were  scarce, 
but  was  found  to  be  very  complex  in  places  where  outcrops  were  fre- 
quent or  continuous,  as,  for  example,  along  the  seacoast  of  the  Darby 
peninsula;  profound  disturbance  alone  could  explain  the  facts  there 
revealed.  In  the  areas  of  post-metamorphic  rocks,  on  the  other  hand, 
the  structures,  although  deformed,  showed  larger  scale  and  conse- 
quently less  complex  relations.  For  this  reason  the  two  areas  may  be 
treated  more  or  less  independently. 

The  folds  and  faults  produced  by  the  post-Cretaceous  deforma- 
tion are  most  strongly  marked  in  the  Nulato-Norton  Bay  region. 
Here  the  predominant  structure  trends  northeast-southwest  and  is 
very  pronounced.  This  structure  has  had  a marked  effect  upon  the 


Figure  8. — Diagrammatic  section  west  of  Traverse  Peak. 


distribution  of  the  topographic  features,  such  as  ridges  and  valleys, 
which  are  dominantly  parallel  to  this  direction.  Although  the  trend 
of  the  ridges  is  undoubtedly  due  to  the  structure,  the  surface  in  no 
way  corresponds  to  the  surface  of  the  old  folded  structure;  for, 
although  some  of  the  ridges  are  anticlinal,  many  are  synclinal.  Such 
a condition,  of  course,  would  not  be  produced  unless  long-continued 
erosion  had  dissected  the  hills.  In  the  part  of  the  divide  between  the 
Yukon  and  the  Norton  Bay  drainage  near  Traverse  Peak  the  struc- 
ture is  distinctly  anticlinal,  but  the  present  surface  of  the  hills  must 
be  many  thousand  feet  below  the  former  surface.  Figure  8 shows 
in  diagrammatic  fashion  the  observations  made  eastward  from  near 
the  forks  of  the  Inglutalik,  2 miles  below  camp  B8,  to  the  top  of 
Traverse  Peak.  The  observed  dips  are  indicated  by  the  heavy  lines, 
whereas  the  implied  consequences  are  shown  by  dotted  lines.  In  this 


88 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


figure  the  vertical  height  of  the  structure  is  undoubtedly  somewhat 
too  great,  for  faults  of  greater  or  less  displacement  are  to  be  expected. 
While,  therefore,  the  diagram  is  not  to  be  taken  too  literally,  it  indi- 
cates that  an  enormous  cover  has  been  removed;  hence  the  divide  is 
an  erosional  rather  than  a constructional  feature.  In  this  connection, 
it  should  be  pointed  out  that  the  thickness  of  the  Shaktolik  group, 
indicated  in  this  diagram,  can  not  be  taken  as  indicating  the  total 
thickness  of  the  cover,  for  the  top  of  the  group  is  not  exposed  near 
the  forks  of  the  creek  in  the  bowl  of  the  syncline,  and  there  is  no 
evidence  as  to  the  distance  to  the  upper  surface  of  the  group  that  has 
been  removed  by  erosion. 

Considered  in  a broad  way  the  region  from  the  Buckland-Kiwalik 
divide  eastward  to  the  Kaiyuh  Hills  is  synclinal,  the  folding  having 
a general  northeast-southwest  trend.  It  is  complicated  by  numerous 
folds  and  faults,  so  that  when  examined  in  detail  its  larger  features 
become  obscured,  and  in  general  it  shows  a rim  of  the  oldest  Creta- 
ceous rocks  near  the  margins,  with  younger  rocks  toward  the  center  of 
the  synclinorium.  In  the  central  part  of  the  area  the  post- Cretaceous 
deformation  has  been  expressed  mainly  by  folding,  but  toward  the 
western  part  of  the  region,  at  least,  faults  of  enormous  throw  seem  to 
have  resulted.  This  fact  is  clearly  shown  by  the  relation  of  the  Un- 
galik  conglomerate  near  the  Tubutulik.  This  block,  isolated  from  the 
rest  of  the  Cretaceous  area  by  a belt  of  schistose  rocks  of  Paleozoic  age 
or  older,  appears  as  a down-faulted  remnant  of  the  former  extension 
of  the  Ungalik  conglomerate  of  the  East  Fork  of  Ivoyuk  River.  So 
also  the  Cretaceous  area  west  of  the  mouth  of  the  Koyuk  seems  to 
be  an  inset  block  of  sandstone  dropped  down  so  far  that  the  con- 
glomerate which  should  underlie  it  is  not  exposed.  The  absence  of 
the  conglomerate  at  this  place  shows  conclusively  that  the  beds 
could  not  have  been  folded  into  their  present  condition,  but  must 
have  been  inset  by  faulting.  No  estimate  of  the  displacement  repre- 
sented by  this  fault  was  obtained,  but  it  Avas  at  least  many  hundred 
feet  and  was  possibly  several  thousand  feet. 

As  suggested  in  the  preceding  paragraph,  it  is  believed  that  many 
if  not  most  of  the  larger  faults  in  the  area  dominantly  occupied  by 
the  Cretaceous  rocks  were  produced  at  the  same  general  period  as 
the  folding  in  the  central  part  of  the  region.  Folds  passing  into 
faults  are  well-known  phenomena,  and  it  seems  reasonable  that  where 
the  deformation  was  greatest  the  beds  woidd  be  more  apt  to  rupture 
and  produce  faults.  That  the  regions  outside  of  the  great  Cretaceous 
area  were  the  most  uplifted  is  indicated  by  the  fact  that  sediments 
of  this  age  have  been  removed  by  erosion  more  extensively  than  in 
the  Nulato-Norton  Bay  region.  It  is  not  believed  that  the  absence  of 
Cretaceous  rocks  over  much  of  the  area  of  metamorphic  rocks  which 
form  the  rim  of  the  present  basin  is  owing  to  their  not  having  been 


NORTON  BAY-NULATO  REGION,  ALASKA. 


89 


originally  deposited  there.  The  reason  for  this  belief  rests  on  the 
inset  blocks  on  the  Tubutulik  and  at  the  Ramparts  of  the  Yukon  as 
well  as  at  many  of  the  less  Avell  known  localities.  It  seems  that  these 
blocks  point  conclusively  to  a former  much  greater  extension  of  this 
rock  system,  which  has  been  gradually  decreased  as  erosion  removed 
the  liiger  parts  and  exposed  the  underlying  rocks.  As  to  the  posi- 
tion of  the  former  shore  line  of  the  maximum  extent  of  the  Creta- 
ceous sea  there  is  no  known  evidence,  and  it  is  doubtful  whether  proof 
can  be  obtained,  as  erosion  has  so  extensively  removed  the  traces. 

To  return  to  the  faults  in  the  Cretaceous  area — it  has  been  sug- 
gested that  many  of  the  larger  faults  have  been  the  result  of  .the  post- 
Cretaceous  deformation,  and  the  reasons  for  this  belief  have  been 
stated.  Although  the  validity  of  this  argument  may  be  questioned, 
as  it  rests  so  much  on  hypothesis,  there  can  be  no  doubt  that  certain 
faults  belong  to  this  period.  Numerous  examples  were  observed 
along  Shaktolik  River  where  closely  appressed  folds  have  been 
broken  and  faults  have  been  produced  by  the  deforming  forces.  It  is 
a notable  fact  well  shown  by  the  excellent  exposures  along  the  canyon 
walls  of  the  Shaktolik  that,  where  the  deformation  is  most  intense, 
as  indicated  by  the  close  folding,  faults  are  most  numerous.  Of 
course,  it  is  only  at  intervals  that  the  age  of  these  faults  with  respect 
to  the  folding  can  be  determined  by  direct  observation.  The  inti- 
mate relation,  however,  of  faulting  to  areas  of  close  folding  and  the 
observed  passage  of  folds  into  faults  make  it  almost  certain  that  much 
of  the  folding  and  faulting  were  contemporaneous. 

That  there  has  been  faulting  in  the  Cretaceous  area  subsequent  to 
the  main  period  of  deformation  is  clearly  shown  by  the  fact  that 
faults  have  been  observed  cutting  the  post-Cretaceous  dikes  which 
form  apophyses  of  the  Christmas  mountain  intrusion.  Faults  of  this 
age  were  observed  near  camp  A16,  on  the  Ungalik,  and  there  was 
evidence  that  larger  movements  had  taken  place  elsewhere.  It  is 
to  be  borne  in  mind,  however,  that  the  opportunities  for  obtaining 
data  on  the  age  of  the  faults  are  infrequent,  and  it  is  bv  no  means 
improbable  that  faults  later  than  the  post-Cretaceous  deformation 
may  be  more  common  and  widespread  than  the  single  faulted  area 
noted  indicates.  So  far  as  known,  however,  it  is  certain  that  none 
of  the  later  faults  exercise  a direct  effect  on  the  present  topography. 

As  has  already  been  pointed  out,  the  period  of  post-Cretaceous 
deformation  was  one  of  mountain  building,  and  its  effects  were  not 
confined  to  the  Cretaceous  area  between  the  Yukon  and  the  Ivoyuk, 
but  were  extended  to  the  already  greatly  deformed  rocks  of  Seward 
Peninsula.  Traces  of  this  folding  may  still  be  recognized  in  the 
dominant  north-south  trend  of  many  of  the  structures.  An  illustra- 
tion of  this  trend  is  seen  in  the  band  of  Paleozoic  rocks  along  the 
east  side  of  the  Darby  Range  and  also  in  the  various  limestone  bands 


90 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


west  of  this  range.  Although  this  direction  is  also  the  trend  of  the 
Darby  Range  and  of  the  highland  of  the  Buckland-Kiwalik  divide, 
the  rocks  in  both  of  which  are  older  than  the  Cretaceous,  it  seems 
probable  that  this  form  is  a post-Cretaceous  feature,  so  that  the 
intrusions  were  not  controlled  by  this  structure.  According  to  this 
explanation  the  Darby  and  the  Kiwalik  hills  are  due  to  the  post- 
Cretaceous  deformation,  and  the  fact  that  the  igneous  rocks  of  the 
two  areas  are  not  continuous  or  aligned  gives  support  to  this  inter- 
pretation. It  is  not  intended,  however,  to  assert  that  these  hills 
necessarily  mark  the  axes  of  the  deformation,  for  it  is  believed  that 
these  areas  are  highlands  mainly  because  the  rocks  of  which  they  are 
formed  have  been  strengthened  and  made  resistant  by  the  intrusives 
which  characterize  them. 

A difficulty  in  the  way  of  the  acceptance  of  this  interpretation  is 
the  undeformed  character  of  the  granites  and  other  igneous  rocks 
of  these  areas.  Although  on  the  face  this  is  a vital  objection,  the  in- 
controvertible fact  that  these  rocks  form  the  bowlders  in  the  Ungalik 
conglomerate  makes  them  certainly  older  than  the  post-Cretaceous 
deformation.  Either,  then,  these  rocks  were  unaffected  during  this 
period  of  mountain  building  or  else  they  passed  through  it  without 
marked  folding  and  shearing.  That  a belt  of  rocks,  averaging  in 
width  only  about  6 miles  and  nowhere  over  12  or  14  miles  wide, 
should  have  withstood  pressures  great  enough  to  fold  perhaps 
G miles  of  Cretaceous  sediments  into  great  waves  as  one  would  fold 
the  leaves  of  a magazine  is  almost  inconceivable.  It  seems  far  more 
probable  that  the  deformation  that  occurred  in  this  part  of  the  field 
was  characterized  by  faults  rather  than  by  folds.  According  to  this 
explanation  great  blocks  practically  undeformed  may  have  been  up- 
lifted and  oriented  in  a north-south  direction  without  having  been 
folded  or  without  having  had  pronounced  shearing  induced. 

With  such  pronounced  post-Cretaceous  deformation  noted  so  widely 
throughout  the  region,  it  is  evident  that  the  untangling  of  earlier 
structures  is  possible  only  by  the  most  detailed  investigation.  Inas- 
much as  such  studies  have  not  yet  been  made,  it  follows  that  interpre- 
tations are  to  be  regarded  as  tentative  and  as  indicating  the  kind  of 
structures  to  be  expected  rather  than  as  stating  the  precise  structure 
at  any  particular  locality.  In  order  to  emphasize  the  complex  char- 
acter of  some  of  the  pre-Cretaceous  deformation  a few  examples  of 
field  observation  may  not  be  out  of  place. 

Plate  XIII,  A , shows  one  of  the  closely  appressed  folds  in  the 
immediate  neighborhood  of  the  Omilak  mine  and  very  clearly  illus- 
trates the  point  in  hand.  This  illustration  is,  of  course,  only  one  of 
the  smaller  folds,  for,  as  is  indicated  by  the  hammer,  which  is  about 
18  inches  long,  the  outcrop  is  only  about  10  to  12  feet  high.  It  should 
also  be  noted  in  this  view  that  although  the  folded  character  of  the 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  449  PLATE  XIII 


B.  FOLDED  AND  SHATTERED  LIMESTONE  ON  OPHIR  CREEK. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


91 


beds  is  very  clearly  shown  in  the  central  and  left-hand  portion  of  the 
picture,  the  beds  on  the  opposite  sides  of  the  axis  in  the  right-hand 
portion  are  so  nearly  parallel  that  except  under  favorable  conditions 
of  exposure  the  divergence  might  be  attributed  to  minor  faults  or 
might  even  pass  undetected. 

Where  the  beds  are  so  closely  folded  it  is  evident  that  it  is  very 
difficult,  if  not  impossible,  to  distinguish  between  the  two  or  more 
periods  of  deformation  known  to  have  affected  the  region.  For 
instance,  the  fold  shown  in  Plate  XIII,  A,  has  a strong  pitch  to  the 
west — that  is,  away  from  the  point  of  view.  Whether  this  pitch  is 
due  to  the  same  deformation  which  overthrew  the  fold  toward  the 
north  (to  the  right)  or  whether  the  overturned  fold  has  itself  subse- 
quently been  folded  parallel  to  a north-south  axis  is  not  known.  Figure 
9 shows  in  diagrammatic  manner  the  conditions  probably  existing  at 
this  place,  the  right-hand  part  of  the  diagram  representing  the  part 
of  the  area  shown  in  Plate  XIII,  A.  As  the  north-south  folds  of  the 
post-Cretaceous  deformation  are  the  latest  mountain  building  in  the 
region,  it  follows  that  the 
east-wTest  trend  noted  in  the 
vicinity  of  the  Omilak  mine 
preceded  that  period  and 
was  later  deformed  by  the 
forces  producing  the  north- 
south  trend.  On  the  other 
hand,  it  is  entirely  within 
the  bounds  of  reason  to  sup- 
pose that  in  a period  of  deformation  such  as  that  which  followed  the 
laying  down  of  the  Cretaceous  deposits  the  dynamic  forces  would  not 
be  equal  over  the  entire  area;  hence  the  sag  shown  in  the  diagram 
might  occur  at  a place  marking  inequality  of  the  deforming  force. 

Whatever  the  final  determination  may  be  as  to  the  origin  of  this 
structure,  the  fact  remains  that  it  is  by  no  means  uncommon  in  the 
region.  The  irregular  distribution  of  the  different  formations  seems 
to  suggest  a structure  of  this  kind.  For  instance,  if  the  present 
erosion  surface  be  indicated  by  a plane  passing  through  the  dotted 
line  AA  in  figure  9,  it  is  evident  that  the  limestone  bed  BB  would 
be  exposed  in  the  field  by  two  isolated  outcrops  in  which  the  fold, 
if  it  was  as  closely  appressed  as  the  one  shown  in  Plate  XIII,  A , 
would  probably  escape  detection,  owing  to  the  close  parallelism  of  the 
two  limbs. 

The  reverse  of  the  condition  shown  in  figure  9 might  also  occur 
where  the  field  relations  would  be  as  though  the  diagram  were  looked 
at  upside  down  and  the  erosion  surface  were  still  represented  by  the 
dotted  line  AA.  Under  this  condition  only  the  synclinal  bowls  where 
the  rocks  had  been  folded  down  lowest  in  the  latest  period  of  deforma- 


— A 


Figure  9. 


-Diagram  showing  folding  in  two  direc- 
tions. 


92  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

tion  would  be  preserved.  This  condition  might,  of  course,  expose 
either  anticlines  or  synclines  of  the  earlier  period  of  deformation, 
so  that  a single  observation  would  afford  no  conclusive  idea  of  the 
relations. 

With  each  subsequent  folding  some  of  the  earlier  features  are 
obliterated  and  structures  formed  in  the  previous  period  of  deforma- 
tion become  contorted.  Plate  XIII,  B , shows  a limestone  outcrop 
about  a quarter  of  a mile  above  Dutch  Creek  on  Ophir  Creek  in  the 
Council  region  that  has  very  evidently  been  folded  so  that  now  the 
dominant  structure  is  standing  vertical.  When  this  exposure  is 
studied  in  detail  it  is  evident  that  the  thing  which  has  been  folded  is 
a previous  cleavage  and  not  the  bedding.  In  places,  of  course,  the 
bedding  corresponds  to  the  cleavage,  but  in  this  picture  it  is  evident 
that  it  is  a cleavage  that  has  been  folded.  This  indicates  that  two 
periods  of  folding  have  taken  place;  in  one  the  cleavage  was  pro- 
duced, and  in  another  it  was  folded. 

Examples  of  this  twofold  structure  are  to  be  seen  in  all  parts  of 
the  field  and  are  not  limited  to  any  particular  kind  of  rock,  except 
that  two  structures  are  never  seen  in  the  later  igneous  rocks  nor  in 
the  Cretaceous  sediments.  Evidences  of  two  structures  are  particu- 
larly notable  in  the  schists  and  limestones,  but  the  black  quartzites 
of  the  Paleozoic  rocks  seem  to  have  fractured  rather  than  folded  in 
the  post-Cretaceous  period  of  deformation.  Usually  in  the  schists 
the  later  folding  is  recognized  by  minor  transverse  plications.  The 
small  hand  specimens  are  the  miniatures  of  the  larger  features,  and 
the  reason  for  the  difficulty  in  recognizing  the  larger  ones  is  the 
complexity  of  the  structure  and  the  absence  of  clearly  distinguish- 
able horizons  in  the  schist  complex.  On  the  1,200- foot  hill  east  of 
camp  C 4 almost  every  piece  of  float  gives  striking  illustration  of 
this  double  plication. 

Of  the  existence  of  the  two  periods  described  there  can  be  no  doubt, 
for  they  have  been  recognized  not  only  in  this  field  but  in  many  other 
parts  of  Seward  Peninsula.  Moffit,  who  studied  the  region  to  the 
north  where  the  rocks  are  similar  in  many  respects  to  those  found 
in  the  southeastern  part  of  the  peninsula,  says:® 

This  complex  (the  metamorphic  group),  both  sedimentary  and  igneous  in 
origin,  was  affected  by  the  two  movements  mentioned,  which  acted  in  very 
different  directions.  One  produced  a structure  in  which  the  axes  of  the  folds 
extend  in  an  east-west  direction,  and  is  most  plainly  expressed  in  the  uplift 
constituting  the  Kigluiak  and  Bendeleben  mountains.  * * * This  east-west 

structure  corresponds  in  the  direction  of  its  folds  with  the  main  structural  lines 
of  the  whole  of  western  Alaska,  and  is  believed  to  have  been  produced  before  the 
deposition  of  the  coal  beds ; that  is,  before  Cretaceous  or  lower  Tertiary  time. 

The  second  movement  resulted  in  the  production  of  folds  whose  axes  have 
a general  north-south  direction  and  are  the  dominant  structural  feature  of  the 
northern  portion  of  the  peninsula. 

a Moffit,  F.  II.,  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska : Bull.  U.  S. 
Geol.  Survey  No.  247,  1905,  p.  35.  ^ 


NORTON  BAY-NULATO  REGION,  ALASKA. 


93 


It  has  already  been  suggested  that  the  schists  which  underlie  the 
Paleozoic  rocks  were  probably  deformed  prior  to  the  deposition  of 
that  member  of  the  stratigraphic  sequence  -and  that  the  later  rocks 
lie  unconformably  upon  them.  This  is  a difficult  thing  to  prove  and 
is  advanced  tentatively.  There  is  no  place  where  the  underlying  and 
the  overlying  rocks  occur  so  intimately  associated  that  the  possibility 
of  faulting  is  precluded,  and,  although  the  underlying  rocks  are 
much  more  schistose  and  apparently  more  deformed,  there  is  neces- 
sarily the  uncertainty  as  to  the  weight  that  should  be  given  to  this 
evidence  when  applied  to  lithologically  different  rocks.  In  spite  of 
these  objections  it  is  believed  that  there  was  a period  of  profound 
pre-Silurian  deformation.  Definite  proofs  of  this  event  have  been, 
in  the  main,  removed  by  the  two  subsequent  periods  of  mountain 
building,  but  the  constant  greater  metamorphism  of  the  supposedly 
older  schists,  the  field  relations  of  the  two  groups,  and  the  presence 
of  certain  structures  in  the  older  schists  not  found  in  the  Paleozoic 
rocks  lead  to  the  conclusion  that  there  was  a period  of  pre-Silurian 
deformation. 

If  this  hypothesis  proves  to  be  correct,  it  follows  that  an  exceed- 
ingly complex  arrangement  of  the  lithologic  members  of  the  older 
schists  is  to  be  expected,  and  that  the  final  determination  of  the  suc- 
cession in  that  group  will  be  accomplished  with  the  utmost  difficulty. 
For  the  purposes  of  this  paper,  however,  it  will  be  sufficient  to  point 
out  that  the  effect  of  each  period  of  deformation  has  been  to  make 
the  distribution  of  the  older  rocks  more  and  more  irregular,  and,  if 
the  term  may  be  applied  to  distribution,  smaller  “ textured.”  As 
to  the  trend  of  the  deformation  of  the  oldest  folding,  there  are  no 
data  available  on  which  to  base  even  an  approximation. 

HISTORICAL  GEOLOGY. 

To  one  who  has  followed  the  preceding  descriptions  with  geologic 
insight  the  successive  events  which  occurred  in  the  region  have 
already  been  given.  As  the  facts  for  making  a relative  chronology, 
however,  have  been  scattered  through  many  pages,  it  seems  desirable 
to  collect  these  details  into  sequential  order  which  shall  give  an 
epitome  of  the  geologic  history  of  the  Nulato-Council  region. 

The  oldest  recorded  event  from  which  a start  can  be  made  was  the 
laying  down  of  quartzose  and  calcareous  sediments  over  much  of 
what  is  now  western  Alaska  under  presumably  marine  conditions. 
No  definite  age  for  this  event  can  be  given.  It  was,  however,  un- 
doubtedly earlier  than  the  Silurian.  From  the  evidence  secured  by 
Kindle  in  the  York  region  of  western  Seward  Peninsula,  where  the 
Ordovician  and  Upper  Cambrian  seem  to  form  a continuous  rela- 
tively uninterrupted  sequence  overlying  similar  rocks,  there  is  some 


94 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


warrant  for  considering  the  oldest  rocks  as  possibly  pre-Cambrian. 
This  suggestion  as  to  the  age  is  to  be  regarded  only  as  a working 
hypothesis  and  is  by  no  means  definitely  proved. 

After  the  deposition  of  these  sediments  there  were  probably  some 
veins  formed  which  are  now  represented  by  the  knotted  and  contorted 
quartz  strings  found  in  the  older  schists.  Either  coincident  with  this 
venation  or  following  it,  probably  the  latter,  a period  of  mountain 
building  ensued  in  which  the  quartzose  and  calcareous  sediments 
previously  deposited  were  consolidated  and  deformed  and  cleavage 
wTas  probably  developed.  Erosion  followed  and  sediments  from  this 
old  land  were  carried  out  and  deposited  in  the  sea.  This  process 
must  have  continued  for  such  a long  time  that  the  highlands  were 
reduced  by  erosion  and  the  region  subsequently  became  depressed 
below  the  marine  waters,  for  the  rocks  formed  of  the  waste  thus 
washed  from  the  land  were  apparently  deposited  unconformably 
on  the  underlying  rocks.  If  the  tentative  assumption  of  the  pre- 
Cambrian  age  of  the  oldest  sediments  is  correct,  this  period  of  moun- 
tain building  may  mark  the  gap  between  the  Paleozoic  and  the  pre- 
Paleozoic.  In  this  period  undoubtedly  many  oscillations  and  minor 
deformations  may  have  occurred  which  are  now  unrecognizable. 

After  the  period  of  mountain  building  the  material  eroded  from 
the  land  mass  was  deposited  in  the  marine  waters  off  the  coast. 
The  land  from  which  this  waste  was  derived  was  remote  from 
the  area  under  consideration,  for  the  sediment  derived  from  it  that 
now  covers  part  of  Seward  Peninsula  was  laid  down  as  limestone. 
In  the  Nulato-Council  region  this  deposition  corresponds  with  the 
laying  down  of  the  Paleozoic  rocks.  In  the  western  part  of  the  penin- 
sula, however,  as  has  already  been  pointed  out,  there  are  limestones 
containing  Cambrian  and  Ordovician  fossils,  and  as  there  is  no  known 
break  between  these  limestones  and  the  Silurian-Devonian-Carbonif- 
erous (?)  rocks  of  this  region  it  is  assumed  that  the  period  of  dep- 
osition may  have  continued  practically  uninterruptedly  from  the 
Cambrian  to  the  Devonian  or  Carboniferous.  During  most  of  this 
time  limestones  were  being  laid  down,  but  the  intercalation  of  highly 
quartzose  carbonaceous  sediments,  such  as  those  now  found  near 
Mount  Kwiniuk,  indicates  movements  of  the  sea  floor  and  changes 
in  relation  to  the  source  of  waste  supply. 

After  the  deposition  of  the  Paleozoic  rocks  there  was  probably  an 
uplift,  for  the  next  event  recorded  was  the  intrusion  of  greenstones, 
some  of  which  formed  surface  flows.  Such  flows  could  hardly  have 
taken  place  while  the  limestones  were  being  laid  down,  and  it  is 
therefore  necessary  to  believe  that  a part  of  Seward  Peninsula  was 
at  that  time  dry  land.  This  period  of  greenstone  intrusion  was  well 
marked  through  many  parts  of  Alaska  and  has  been  recognized  not 
only  in  Seward  Peninsula,  but  also  in  the  northern  part  of  the 


NORTON"  BAY-NULATO  REGION,  ALASKA. 


95 


Koyukuk,  in  the  basin  of  the  Melozitna,  and  in  the  Kaiyuh  hills.  If 
the  extrusions  of  greenstone  materials  took  place  on  land  they  must 
have  unconformably  overlain  the  older  rocks.  In  the  Nulato-Norton 
Bay  region  none  of  the  effusive  types  were  recognized,  but  farther 
west  effusive  character  was  strongly  suggested  by  the  exposures  in 
the  Solomon-Casadepaga  quadrangles.  In  the  central  Yukon  region 
the  age  of  the  greenstone  intrusion  is  Devonian.  For  this  reason  it 
is  possible  that  in  the  determination  of  the  fossils  from  the  sedi- 
mentary rocks  as  either  Devonian  or  Carboniferous,  preference  should 
be  given  to  the  older  rather  than  the  younger  system.  In  the  Copper 
River  region  and  in  southeastern  Alaska,  on  the  other  hand,  a period 
of  greenstone  effusion  has  been  described  as  Carboniferous  or  later,  so 
that  correlation  by  analogy  is  inconclusive. 

With  the  intrusion  of  the  greenstones  there  was  some  local  or  con- 
tact metamorphism  of  the  rocks  they  penetrated,  but  the  effects  were 
slight.  There  was  also  the  formation  of  some  veins,  but  many  of  the 
older  veins  were  already  in  the  Paleozoic  rocks  before  the  intrusion 
by  the  greenstone,  for  in  places  the  veins  are  abruptly  cut  off  by  the 
later  rock.  With  the  greenstone  probably  a little  mineralization  was 
introduced,  but  its  effects  upon  the  metalliferous  resources  of  the 
region  were  slight. 

After  the  formation  of  the  greenstones  a period  of  mountain  build- 
ing ensued  in  which  the  previously  formed  rocks  were  metamor- 
phosed dynamically  and  profoundly  faulted  and  folded.  When  this 
occurred  can  not  be  told  with  definiteness  owing  to  the  uncertainty 
of  the  ages  of  the  Paleozoic  rocks  and  the  greenstones.  From  the 
evidence  afforded  by  other  parts  of  Alaska  there  are  two  dates  to 
which  the  deformation  may  reasonably  be  assigned — one  is  in  the  late 
Devonian,  and  the  other  is  in  the  early  part  of  the  Mesozoic.  If  the 
Devonian  instead  of  the  Carboniferous  age  of  the  sedimentary  rocks 
is  assumed,  it  follows  that  either  of  these  periods  will  fulfill  the 
requirements  of  the  field  evidence.  If,  on  the  other  hand,  however, 
the  upper  part  of  the  deposits  is  Carboniferous  it  is  evident  that  the 
period  of  mountain  building  following  the  deposition  and  consolida- 
tion of  the  Paleozoic  sediments  and  their  intrusion  by  the  green- 
stones must  have  been  the  one  occurring  in  the  Mesozoic.  No  con- 
clusive evidence  on  this  point  has  been  obtained,  and  the  question 
must  still  remain  an  open  one. 

As  a result  of  the  deformation,  the  rocks  were  cleaved  and  folded 
and  probably  high  mountains  were  formed.  As  soon  as  they  were 
formed,  erosion  began  to  wear  them  down  and  to  transport  the  mate- 
rial toward  the  sea.  No  clear  idea  is  possible  of  how  long  this  proc- 
ess continued  uninterruptedly,  for  the  only  part  of  the  Mesozoic 
represented  by  stratified  rocks  in  this  field  is  Cretaceous.  An  inter- 
ruption occurred  some  time  after  the  mountain  building  and  prior 


96 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


to  the  deposition  whereby  igneous  activity  became  dominant.  There 
is  no  evidence  as  to  whether  during  the  early  part  of  this  vulcanic 
cycle  the  region  was  land  or  was  beneath  the  sea,  but  for  the  purposes 
of  the  present  report  this  is  not  of  great  importance. 

The  first  recorded  intrusion  of  this  period  was  the  formation  of 
diorites,  which  were  subsequently  intruded  by  granites,  and  these  in 
turn  were  intruded  by  other  diorites.  Although  these  various  phases 
could  not  have  been  formed  within  a short  time  of  each  other  (for 
each  of  them  had  cooled  and  consolidated  sufficiently  before  the  next 
succeeding  intrusion  so  that  they  broke  into  angular  fragments), 
from  a geological  standpoint  they  were  closely  associated  in  age  and 
may  be  considered  as  a unit.  Evidence  as  to  the  age  of  these  rocks  is 
afforded  only  by  analogy  with  other  parts  of  Alaska.  In  the  Mat- 
anuska-Talkeetna  region  of  south  central  Alaska,  Knopf  and  Paige 
determined  the  age  of  the  great  granodiorite-diorite  intrusions  as 
later  than  the  Middle  Jurassic  and  earlier  than  the  deposition  of  the 
late  Jurassic  strata.®  The  Wrights  in  southeastern  Alaska  stated 
that,  although  the  date  of  the  major  period  of  intrusive  activity  (the 
time  of  the  Coast  Range  intrusion)  was  in  doubt,  it  continued  at  least 
until  late  Middle  Jurassic  time.6 

Although  long-range  correlations  of  this  sort  are  clearly  liable  to 
gross  errors,  the  absence  of  other  data  is  sufficient  justification  for 
tentatively  accepting  the  only  available  facts  at  hand.  On  this 
assumption  the  most  reasonable  age  determination  of  the  intrusives 
of  the  Darby  and  Bendeleben  mountains  is  that  they  are  Middle 
Mesozoic. 

In  the  section  dealing  with  the  descriptive  geology  of  the  pre-Cre- 
taceous igneous  rocks  it  was  stated  that  in  the  Kiwalik-Buckland 
divide  there  were  ancient  effusives  along  the  flanks  of  that  highland. 
It  is  practically  inconceivable  that  effusive  rocks  of  geologically  the 
same  age  as  granular  intrusives  should  occur  in  contact  with  those 
intrusives.  The  granular  rocks  by  their  texture  require  relatively 
slow  cooling  under  considerable  cover.  It  follows,  therefore,  that 
when  the  intrusives  of  the  Kiwalik-Buckland  highland  were  injected 
there  had  been  a considerable  thickness  of  strata  over  the  region, 
which  was  removed  before  the  effusion  of  the  older  lavas.  No  pre- 
cise measure  of  the  time  required  for  eroding  the  superincumbent 
rocks  can  be  made,  but  it  must  have  taken  a long  time.  After  erosion 
had  exposed  the  plutonic  rocks  of  the  mid-Mesozoic,  andesitic  lavas 
were  extruded. 

During  the  latter  part  of  this  period  this  portion  of  Seward  Penin- 
sula, at  least,  must  have  been  land.  Gradual  submergence  occurred 

® Paige,  Sidney,  and  Knopf,  Adolph,  'Geologic  reconnaissance  in  Matanuska  and  Tal- 
keetna  basins,  Alaska  : Bull.  U.  S.  Geol.  Survey  No.  327,  1907,  p.  20. 

b Wright,  F.  E.  and  C.  W.,  Ketchikan  and  Wrangell  mining  districts,  Alaska ; Bull, 
p.  S.  Geol.  Survey  No.  347,  1908,  p.  76. 


NORTON  BAY-NULATO  REGION,  ALASKA.  97 

and  marine  waters  beat  against  the  shore  forming  a heavy  conglom- 
erate which,  as  time  went  on  and  the  shore  line  gradually  encroached 
farther  and  farther  on  the  land,  was  buried  in  the  deeper  parts  of 
the  basin  by  finer  sediments.  At  no  time,  however,  was  the  water  in 
the  basin  very  deep,  for  mud-flat  markings  and  cross  bedding  are  ob- 
servable at  many  places.  Probably  by  stages  more  or  less  equal  with 
the  filling  of  the  basin  with  detritus  the  bottom  sank  until  a great 
thickness  of  sediment  was  deposited.  Where  the  farthest  encroach- 
ment of  the  sea  on  the  land  occurred  is  not  known,  but  marine  waters 
must  have  covered  the  larger  part  if  not  the  whole  of  what  is  now 
Seward  Peninsula.  In  this  sea  the  deposits  accumulated  and  covered 
the  pre-existing  topography  that  had  not  been  effaced  by  the  beat  of 
the  sea  upon  it. 

The  geologic  age  of  the  sediments  deposited  during  this  period 
is  Cretaceous.  As  has  already  been  stated,  on  page  56,  the  Ungalik 
conglomerate  at  the  base  may  be  Lower  Cretaceous,  but  the  upper 
part,  or  Shaktolik  group,  contains  no  fossils  other  than  of  Upper 
Cretaceous  age.  In  other  parts  of  Alaska  there  has  been  reported  a 
pronounced  break  between  the  Upper  and  the  Lower  Cretaceous  and 
the  two  are  in  uncomformable  relations.  In  this  province  no  break 
was  noted.  If,  however,  subsequent  studies  should  show  a period 
of  diastrophism  between  the  Upper  and  the  Lower  Cretaceous  it 
would  seem  rather  conclusive  evidence  that  the  Ungalik  conglomerate 
is  of  Upper  Cretaceous  age,  for  the  fossil  evidence  which  seemed  to 
indicate  a Lower  Cretaceous  age  is  very  weak.  Under  such  conditions 
the  Lower  Cretaceous  would  be  represented  in  Seward  Peninsula  by 
the  erosion  interval  at  the  base  of  the  Ungalik  conglomerate. 

Succeeding  the  period  of  Cretaceous  deposition  was  the  last  epoch 
of  mountain  building.  By  this  deformation  enormous  folds  and 
faults  were  produced  which  must  have  made  mountain  ranges  of 
great  height.  There  is  no  direct  evidence  as  to  the  time  when  this 
folding  occurred.  From  analogy  with  other  parts  of  Alaska,  how- 
ever, it  is  known  that  there  are  two  possible  ages  to  which  the  epeiro- 
genic  movements  may  be  referred.  In  southwestern  Alaska  the  Kenai 
or  upper  Eocene  is  unconformable  on  the  Upper  Cretaceous.®  This 
unconformity  is  marked  by  a break  in  faunas  rather  than  by  mountain 
building,  but  the  fact  that  in  places  the  Kenai  is  known  to  rest  di- 
rectly upon  the  Jurassic  indicates  a long  period  of  changes.  The 
other  period  to  which  the  great  orogenic  movements  of  the  post- 
Cretaceous  may  be  referred  is  later  than  the  deformation  of  the 
Kenai.  There  is  but  little  to  show  which  of  these  is  the  correct  cor- 
relation, for  there  is  no  Kenai  in  the  region  studied.  With  full 

° Stanton,  T.  W.,  and  Martin,  G.  C.,  The  Mesozoic  section  on  Cook  Inlet  and  Alaska 
Peninsula  : Bull.  Geol.  Soc.  America,  vol,  16,  1905,  p.  410. 

71469°— Bull.  449—11 7 


98 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


recognition  of  this  uncertainty  it  is  believed  that  a pre-Kenai  age  for 
the  period  of  orogenic  movement,  which  closed  the  Cretaceous  deposi- 
tion, fits  more  of  the  known  facts  than  any  other  interpretation. 
According  to  this  hypothesis  the  larger  outlines  of  the  geology  of 
western  Alaska  were  marked  out  before  the  Kenai  and  the  sediments 
of  the  latter  period  were  deposited  mainly  on  the  eroded  surface  of 
the  earlier  rocks  and  mostly  as  fresh  water  deposits. 

After  the  great  post- Cretaceous  deformation,  intrusion  of  granular 
rocks,  such  as  those  of  Christmas  Mountain,  occurred.  It  is  unsafe 
to  assign  a more  specific  age  for  this  period  of  volcanism  than  the 
middle  Tertiary.  Whether  the  mountain  building  was  closed  before 
the  intrusion  is  not  definitely  proved.  The  fact  that  some  of  the  dikes 
from  the  Christmas  Mountain  mass  are  faulted  shows  either  that  the 
deformation  had  not  entirely  ceased  or  that  the  dikes  were  formed 
at  a later  time. 

With  the  conclusion  of  the  period  of  granular  intrusions  and  of 
the  great  post-Cretaceous  deformation,  the  region  as  a whole  has  been 
a land  area  subjected  to  erosion  which  has  continued  down  to  the 
present  time.  An  enormous  amount  of  erosion  is  indicated  before 
the  next  recorded  event  in  the  history  of  this  complex  region.  As  a 
result  of  this  erosion  valleys  were  cut  and  the  region  was  reduced 
from  a mountainous  country  to  one  having  something  like  the  present 
topography.  Then  volcanic  activity  began  and  continued  spasmodi- 
cally from  the  later  part  of  the  Tertiary  almost  down  to  the  present. 
The  recent  basaltic  lavas  of  the  Yukon  and  of  the  Koyuk  and  its 
environs  bear  witness  to  this  period.  As  has  already  been  pointed 
out  some  of  these  lavas  are  so  recent  that  they  overlie  the  gravels  of 
the  Noxapaga  basin,  whereas  others  are  so  much  older  that  they  stand 
at  least  a hundred  feet  above  the  present  streams,  which  have  carved 
their  valleys  through  them. 

Many  of  the  lavas  flow  down  the  lowland  areas  of  the  preexisting 
topography.  In  these  depressions  they  were  consequently  thicker  and 
have  therefore  been  less  thoroughly  removed  by  erosion.  From  the 
distribution  of  the  residual  patches  it  is  therefore  possible  to  recon- 
struct in  a measure  the  former  topography,  and  it  is  from  this  recon- 
struction that  one  is  able  to  state  that  much  erosion  must  have  affected 
the  structure  produced  by  the  post-Cretaceous  deformation  before  the 
effusion  of  the  lavas. 

While  the  volcanism  was  in  progress,  erosion  still  continued  over 
much  of  the  area  and  the  highlands  were  degraded  and  deposits  were 
formed  off  the  coasts.  The  erosion,  however,  did  not  proceed  uni- 
formly, for  there  were  undoubtedly  movements  of  the  earth’s  crust 
whereby  certain  parts  were  uplifted  and  others  depressed.  On  the 
whole,  however,  these  movements  were  gentle,  broad,  regional  uplifts 
and  were  not  acute  mountain-building  deformations.  Because  of 


NORTON  BAY-NULATO  REGION,  ALASKA. 


99 


uplift  movements  the  streams  were  at  times  forced  to  cut  their  chan- 
nels deeper  into  the  bed  rock  of  their  valleys,  but  at  other  times, 
because  of  depression,  they  found  the  rock  floors  too  deep  and  were 
forced  to  lay  down  some  of  the  waste  they  were  transporting,  and 
thus  aggrade  their  courses.  Changes  of  this  sort,  however,  did  not 
exercise  any  considerable  effect  on  the  form  of  the  region  except  to 
reduce  the  relief  consistently. 

After  erosion  and  deposition  had  been  in  progress  for  a long  time 
a change  in  the  climatic  conditions  resulted  whereby  glaciation  of 
the  valley  type  was  developed  in  the  highland  areas.  Apparently 
this  event  took  place  when  the  sum  of  the  preglacial  movements  had 
resulted  in  the  region  standing  relatively  lower  than  it  does  now 
with  respect  to  sea  level  and  grade  level.  The  main  result  of  the 
period  was  to  scour  out  the  mountain  valleys  and  distribute  the  waste 
thus  formed  beyond  the  area  occupied  by  the  ice.  From  fossils  asso- 
ciated with  the  deposits  formed  at  this  time  it  seems  probable  that 
this  occurred  in  the  Pleistocene,  which  was  also  the  period  of  maxi- 
mum glaciation  in  other  parts  of  the  northern  hemisphere. 

As  the  vigor  of  glacial  conditions  abated,  the  glaciers  receded  into 
the  hills  and  finally  disappeared.  A long  time,  however,  is  required 
for  this  process,  as  is  shown  by  the  various  moraines  in  the  Pargon 
Valley  and  elsewhere  in  the  mountain  region.  All  this  time  deposits 
of  glacio-fluviatile,  fluviatile,  and  marine  origin  Avere  being  formed 
in  the  areas  not  occupied  by  the  ice  where  the  conditions  were  favor- 
able. Lava  flows  may  also  have  occurred  at  this  same  time  in  the 
areas  not  occupied  by  the  ice. 

With  the  close  of  glacial  conditions  oscillations  of  the  crust  similar 
to  those  preceding  the  period  of  glaciation  again  become  evident. 
It  is  not  intended  to  imply  that  these  oscillations  ceased  during 
glacial  time,  but  the  evidence  is  so  obscured  that  the  movements  were 
not  recognized.  The  general  result  of  these  postglacial  uplifts  has 
been  to  raise  the  region  somewhat  above  the  relative  position  it  occu- 
pied during  the  Pleistocene.  Apparently,  however,  the  sum  of  the 
recent  upward  movements  has  not  yet  equaled  the  sum  of  the  earlier 
downward  movements,  so  that  the  floors  of  many  of  the  larger  streams 
are  still  below  sea  level.  The  general  recent  uplift  is  shown  in  the 
rock-walled  shallow  canyons  in  which  many  of  the  streams  flow. 

Although  the  late  Tertiary  to  Recent  movements  have  been  de- 
scribed as  resulting  in  certain  general  conditions,  it  should  be  dis- 
tinctly understood  that  these  movements  were  such  that  while  depres- 
sion was  taking  place  in  one  part  of  the  region  uplift  may  have  taken 
place  in  another.  Hence  it  appears  that  deposits  at  the  same  eleva- 
tion above  or  below  sea  level  are  by  no  means  synchronous  and  may 
be  entirely  unrelated  in  origin.  Contemporaneity  of  the  various 
deposits  can  only  be  determined  by  careful  and  detailed  investiga- 


100 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


tions  of  the  region.  Inasmuch  as  many  of  the  problems  of  economic 
importance  are  connected  with  the  correct  correlation  of  the  different 
deposits,  it  is  necessary  that  such  correlations  should  be  searchingly 
investigated  and  not  be  based  on  superficial  examination  or  upon 
apparent  similarity  of  factors  known  to  be  variables. 

In  order  to  summarize  the  history  of  the  region  as  determined 
the  table  shown  in  figure  10  has  been  prepared.  It  is  at  best  but  a 
graphic  representation  of  the  facts  already  given,  and  has  the  disad- 


Pre-Cambrianc -Pre-Paleozoic  sedimentation 

^Vernation 

//\\ 

//  s '\  ^Deformation 

/ ' / s\ 

Cambrian --^Erosion  and  deposition  in  western  Seward  Peninsula 

///  ^ 

Silurian^ ^Paleozoic  sedimentation 

/ 

Devonian^ ^Uplift  (minor) 

"'Greenstone  intrusion 

/X''  . 

^yAems 
Triassic— "Xv  — - £ Erosion 

/' X ^ - 

/'s  ^ " 

Jurassic^—  Granite  and  diorite  intrusions 

"'-Erosion 

X ' 'Effusive  rocks  of  Kiwalik-Buckland  divide 
_ ^'Erosion 

Cretaceous^-- Ungalik  and  Shaktolik  sedimentation 

Eocene Deformation 

Christmas  Mountain  intrusion 

Miocene - Faulting 

Erosion 

Pliocene—-" Basalt  effusion 

"^'Oscillations 
Pleistocene^  ™ - - -Glaciation 
^'Oscillations 

Recent'"'"’” 

Figure  10. — Diagrammatic  summary  of  geologic  history  of  Nulato-Council  region. 


vantage  of  giving  an  appearance  of  finality  to  the  correlations,  some 
of  which  the  text  has  shown  to  be  founded  on  insufficient  data;  for 
these  reasons  it  should  be  regarded  as  a summary  and  should  not  be 
used  independently  of  the  text. 


ECONOMIC  GEOLOGY. 

In  the  preceding  description  of  the  areal  geology  of  the  region  it 
has  been  shown  that  east  of  Ivoyuk  River  the  country  is  formed  of 
late  sedimentary  rocks  that  are  little  if  any  metamorphosed,  whereas 


NORTON  BAY-NULATO  REGION,  ALASKA. 


101 


the  region  to  the  west  of  this  stream  is  predominantly  one  of  schists, 
limestones,  and  igneous  rocks.  So  far  as  has  been  indicated  by 
mining  in  contiguous  areas  the  metamorphic  rocks  are  those  in  which 
deposits  of  gold  may  be  sought  with  some  promise  of  success,  whereas 
the  unmetamorphosed  sedimentary  rocks  are  the  ones  in  which  de- 
posits of  coal  may  be  found. 

PLACERS. 

GOLD  IN  AREAS  OF  UNMETAMORPIIOSED  SEDIMENTS. 

CONDITIONS  OF  PLACER  FORMATION. 

In  the  unmetamorphosed  sedimentary  deposits  the  chances  of  find- 
ing economically  important  gold  deposits  are  relatively  slight,  except 
under  local  conditions.  The  Cretaceous  and  Tertiary  deposits,  the 
unmetamorphosed  sediments,  were  formed  of  material  eroded  from 
the  earlier  rocks  and  deposited  on  the  sea  floor  and  in  estuaries  and 
marshes  in  essentially  the  same  way  that  sediments  are  being  de- 
posited at  the  present  day  off  the  coast.  Some  of  the  present-day 
sediments,  however,  are  auriferous,  and  it  might  be  asked  why  simi- 
lar placers  should  not  be  found  in  the  older  sedimentary  deposits. 
Gold  placers  should  occur  in  the  Nulato-Norton  Bay  region  under 
conditions  similar  to  those  prevailing  in  the  coastal  plain  at  Nome, 
but  there  are  few  places  where  similar  conditions  exist. 

In  order  to  make  clear  the  different  conditions  in  the  two  regions 
it  is  necessary  to  point  out  the  salient  facts  concerning  the  productive 
placers  of  the  coastal  plain — for  instance,  those  at  Nome.  A discus- 
sion of  the  character  of  the  surface  of  the  bed  rocks  is  omitted  as 
not  important  in  bringing  out  the  point  of  the  following  paragraph. 

The  known  placers  are  not  more  than  3 or  4 miles  from  the  old  land 
from  which  the  sediments  were  derived ; the  depth  of  gravel  covering 
the  bed  rock  is  seldom  over  100  feet;  the  gravel  is  as  a whole  fairly 
coarse;  the  rich  ground  occurs  in  ancient  beaches,  which  mark  concen- 
tration by  the  sea;  and  the  country  immediately  adjacent  to  the  rich 
placer  is  heavily  mineralized.  Consider  the  physical  and  geographic 
conditions  which  these  facts  entail.  First,  the  short  distance  from 
the  ancient  shore  line  suggests  that  the  gold  did  not  travel  far  sea- 
ward from  the  place  where  it  might  have  been  formed.  This  is,  of 
course,  a conclusion  which  would  have  been  reached  by  anyone  accus- 
tomed to  the  action  of  gold  in  a sluice  box.  It  might  be  safely  assumed 
that  in  general  the  farther  from  the  source  the  less  gold  there  would 
be,  other  conditions  being  equal.  Evidence  of  the  proximity  of 
the  placer  deposits  to  the  old  land  is  shown  by  the  second  criterion, 
namely,  that  the  depth  of  gravel  is  seldom  over  100  feet.  This  con- 
dition, like  the  preceding,  is  valuable  in  establishing  the  nearness  of 
the  gold  to  its  source.  The  third  fact  also  is  of  value  in  further 


102 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


establishing  this  conclusion,  but  it  is  also  important  as  showing  that 
the  agencies  by  which  this  material  was  transported  were  of  sufficient 
strength  to  permit  considerable  sorting  of  the  gravel  and  thus  to  allow 
concentration  of  the  particles  of  gold.  As  the  coastal  plain  placers 
are  found  along  old  strand  lines  it  follows  that  in  order  to  make  a 
deposit  of  economic  importance  it  is  necessary  to  have  a marked  con- 
centration of  once  disseminated  particles.  It  is,  of  course,  unneces- 
sary to  have  this  concentration  effected  by  the  sea,  for  streams  would 
do  it  equally  well,  as  is  shown  by  the  numerous  creek  placers.  Per- 
haps the  most  important  condition  which  must  be  fulfilled  in  order  to 
make  a rich  placer  is  the  presence  of  a highly  mineralized  area  in  the 
more  or  less  immediate  vicinity.  Without  this,  the  other  conditions 
are  ineffective. 

It  has  also  been  pointed  out  by  others  that  certain  physiographic 
conditions  are  essential  for  the  production  of  placers,  such  as  long 
continued  subaerial  erosion  folloAved  by  rapid  sweeping  off  of  de- 
tritus by  revived  drainage.  As  the  physiographic  history  of  north- 
western Alaska  has  not  yet  been  worked  out  in  sufficient  detail  to 
permit  the  application  of  this  criterion  it  can  not  be  critically  applied 
in  this  discussion. 

If  now  the  Nulato-Norton  Bay  region  is  considered  in  the  light  of 
the  premises  enumerated  above  it  at  once  becomes  evident  that  few 
of  its  conditions  are  analogous  to  those  enumerated.  It  is  true  that 
there  are  places  where  the  Cretaceous  basin  is  in  immediate  contact 
with  the  old  land.  This  has  been  proved  by  the  extension  of  the  basal 
conglomerate  from  near  the  Tubutulik  northward  along  the  east 
side  of  the  Buckland-Kiwalik  divide.  The  conglomerate  was  noted 
also  by  Mendenhall a on  the  Kobuk,  from  which  place  it  swings  south- 
eastward. It  was  recognized,  although  not  correctly  correlated,  by 
Schrader  on  the  Koyukuk  and  by  Dali,  Collier,  and  Spurr  on  the 
Yukon,  and  was  correctly  correlated  by  Maddren  on  the  Yukon  near 
the  Melozitna. 

In  the  belt  occupied  by  the  heavy  conglomerate  the  deposits  were 
certainly  near  enough  the  shore  to  permit  the  formation  of  placers, 
but  the  physical  conditions  under  which  this  conglomerate  was  de- 
posited do  not  seem  to  have  been  well  suited  to  the  unlocking  of  gold 
from  bed  rock.  Instead,  the  bowlders  were  riven  from  sea  cliffs 
and  were  subjected  to  trituration  rather  than  to  decomposition  or  dis- 
integration, and  whatever  gold  may  have  been  in  the  rocks  was  so 
abraded  before  it  was  deposited  that  it  undoubtedly  formed  flour 
gold,  which  would  be  much  more  widely  disseminated  than  flake  or 
shot  gold.  Furthermore,  over  a considerable  part  of  the  region 
where  the  basal  conglomerate  was  seen  by  the  survey  party  the 

a Mendenhall,  W.  C.,  Reconnaissance  from  Fort  Hamlin  to  Kotzebue  Sound,  Alaska : 
Prof.  Paper  U.  S.  Geol.  Survey  No.  10,  1902,  pp.  39-41. 


NORTON  BAY-NULATO  REGION,  ALASKA.  103 

country  rock  forming  the  old  land  shore  line  against  which  the  sedi- 
ments were  deposited  consisted  of  limestones  and  igneous  rocks.  So 
far  as  is  known  from  a careful  study  of  the  known  placer  camps 
farther  west,  practically  no  gold  is  found  in  the  limestones  and  none 
is  known  associated  with  the  granites  or  other  igneous  rocks.  It  will 
be  seen  therefore  that  in  the  shoreward  portion  of  the  metamorphic 
area  the  important  condition  of  near-by  highly  mineralized  country 
rock  from  which  the  sediments  were  derived  is  wanting.  It  is  be- 
lieved, therefore,  that  search  for  commercial  placers,  although  not 
entirely  out  of  the  question  in  the  conglomerate  area,  is  to  be  dis- 
couraged, unless  the  field  evidence  shows  the  existence  of  conditions 
other  than  those  generally  encountered  in  the  basal  member. 

Over  the  greater  part  of  the  Nulato-Norton  Bay  area  it  has  been 
shown  that  the  lower  member  marking  proximity  to  the  old  shore 
line  is  not  exposed.  It  seems  probable  that  through  this  part  of  the 
region  the  deposits  are  much  higher  geologically.  From  the  physical 
character  of  the  sediments  and  from  the  structures  observed,  such 
as  cross  bedding,  it  seems  certain  that  the  higher  geological  members 


Figure  11. — Diagrammatic  cross  section  of  the  Nulato-Norton  Bay  region  during  Creta- 
ceous deposition. 

were  deposited  in  relatively  shallow  water.  This  fact,  however,  does 
not  mean  that  the  deposits  were  near  the  old  land  of  metamorphic 
rocks.  Figure  11  shows  in  diagrammatic  manner  the  conditions 
believed  to  have  prevailed  in  the  Nulato-Norton  Bay  region.  The 
metamorphic  rocks  to  the  left  in  the  figure  may  be  taken  to  represent 
the  schists  of  Seward  Peninsula,  and  those  to  the  right  the  rocks  near 
the  Melozitna;  the  intervening  area  is  the  Nulato-Norton  Bay  region 
at  the  beginning  of  Cretaceous  deposition,  with  sea  level  indicated  by 
the  line  AA.  At  this  stage  conglomerates  were  laid  down  close  to 
the  shore  of  the  old  land  and  sandstones  and  shales  toward  the  center 
of  the  basin.  Gradually  depression  took  place  and  continued  at  such 
a rate  that  the  surface  of  the  deposits  was  always  within  a short  dis- 
tance of  sea  level.  It  is  evident,  therefore,  that  if  this  depression 
continued  until  the  surface  of  the  deposits  and  the  sea  level  stood  at  * 
the  line  BB,  no  part  east  of  C as  far  as  D had  ever  been  close  enough 
to  the  metamorphic  area,  which  is  assumed  to  have  been  the  source 
of  mineralization,  to  have  received  any  notable  amount  of  gold.  Con- 
sequently, in  this  part  of  the  region,  unless  subsequent  folding  ex- 
posed rocks  at  the  surface  outside  of  the  part  included  within  the 


104 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


line  CD,  the  probability  of  finding  auriferous  deposits  is  slight,  and 
then  only  if  the  old  land  area  from  which  the  sediments  were  derived 
was  sufficiently  mineralized  to  afford  placer  gold. 

It  has  been  the  object  in  the  preceding  paragraphs  to  point  out 
that  on  the  whole  the  chances  of  finding  gold  in  the  area  of  unmeta- 
morphosed rocks  are  slight.  From  the  fact  that  only  under  excep- 
tional conditions  are  valuable  deposits  likely  to  be  found  it  seems  that 
the  ordinary  prospector  for  gold  should  be  warned  against  spending 
much  time  in  the  region  east  of  Koyuk  River.  Not  only  does  this 
conclusion  seem  sound  from  a theoretical  standpoint,  but  it  was 
learned  from  prospectors  on  the  Inglutalik  that  they  had  been  from 
that  river  eastward  to  beyond  the  Gisasa  and  had  not  been  able  to 
raise  a single  color  of  gold. 

It  is  not  the  purpose  of  this  warning,  however,  to  assert  that  no 
gold  will  be  found  in  the  region,  for  there  are  three  conditions  under 
which  deposits  may  be  found.  The  first  of  these  conditions,  already 
described,  is  that  the  unmetamorphosed  sediments  considered  may 
have  been  originally  deposited  at  no  great  distance  from  the  shore  of 
a mineralized  area  of  metamorphic  rocks.  Such  deposits  might  be 
found  at  several  places,  even  in  the  middle  parts  of  the  basin,  if  sub- 
sequent deformation  brought  the  underlying  rocks  up  to  the  level  of 
erosion.  As  an  example  of  this  condition  may  be  cited  the  area  of 
metamorphic  rocks  which  appear  between  Kwik  and  Koyuk  rivers. 

The  second  condition  which  might  permit  the  formation  of  valuable 
gold  placers  in  the  Nulato-Norton  Bay  region  is  long  continued  con- 
centration of  the  material,  either  b}^  streams  or  by  the  ocean.  Con- 
centration of  this  sort  may  have  been  effected  either  during  the  time 
the  sediments  wTere  being  deposited  or  at  a much  later  time.  Through- 
out the  period  occupied  by  the  deposition  of  the  sands  and  gravels 
the  region  was  apparently  undergoing  almost  uninterrupted  depres- 
sion, so  that,  although  there  was  sorting  by  water,  it.  was  nowhere  so 
effective  as  it  would  have  been  if  the  region  had  been  one  of  alternate 
erosion  and  deposition,  as  the  coastal  plain  at  Nome  has  been.  In 
other  words,  the  ancient  placers  at  Nome  seem  to  have  been  sub- 
jected to  at  least  two  periods  of  concentration,  whereas  the  deposits 
of  the  other  region  seem  to  have  undergone  but  one.  Since  consolida- 
tion, the  sandstones  and  shales  of  the  Cretaceous  have  been  eroded 
by  the  streams  and  a present  day  concentration  is  being  effected. 
Some  of  the  reported  gold  placers  in  the  Yukon  basin  are  probably 
due  to  this  sorting,  but  they  may  have  been  formed  by  original  sorting 
before  the  consolidation  of  the  sediments,  for  little  is  known  about  the 
deposits. 

The  third  type  of  locality  where  search  for  gold  placers  or  lodes 
in  the  area  of  nonmetamorphic  rocks  would  be  warranted  is  at  those 
places  where  mineralization  has  occurred  since  Cretaceous  times. 


NORTON-  BAY-NULATO  REGION,  ALASKA. 


105 


Such  places  are,  so  far  as  known,  closely  associated  with  the  areas  of 
intrusive  igneous  rocks.  The  effusive  rocks  or  lavas  of  Tertiary- 
Recent  age  do  not  seem  to  have  brought  any  valuable  minerals,  ana 
therefore  placers  or  lodes  due  to  post-Cretaceous  mineralization  are 
not  to  be  sought  in  those  areas  where  only  these  rocks  occur. 

Intrusive  rocks  later  than  the  Cretaceous  have  been  noted  at  but 
two  places,  although  a more  detailed  investigation  of  the  area  un- 
doubtedly might  result  in  discovering  others.  The  two  places  where 
these  later  granitic  rocks  have  been  examined  by  the  Survey  party 
are  at  Christmas  Mountain,  east  of  Ungalik  River  and  at  Bonanza 
Creek.  From  reports  of  prospectors  it  seems  that  the  placer-bearing 
gravels  of  Anvik  River  may  have  been  derived  from  a similar  area 
of  intrusive  granitic  rock,  although  too  little  is  known  of  the  geology 
of  the  country  to  advance  this  interpretation  more  than  tentatively. 
Spurr  a in  his  summary  of  the  occurrence  of  gold  in  southwestern 
Alaska  says: 

The  gold  in  this  region  is  by  no  means  so  abundant  as  it  is  along  the  belt 
of  the  Yukon  geanticline,  where  the  ancient  schists  with  their  inclosed  quartz 
veins  are  found.  The  mineralization  of  southwestern  Alaska  is  of  a later  date 
and  not  so  intense  or  widespread.  Within  the  area  examined  by  the  writer’s 
party  last  summer  (1898)  the  Tordrillo  Mountains  are  undoubtedly  the  chief 
seat  of  mineralization,  and  this  appears  to  be  directly  dependent  upon  the  fact 
that  these  mountains  have  also  been  the  chief  seat  of  intrusion  of  igneous  rocks.6 

PLACERS  OF  THE  BONANZA  CREEK  REGION. 

Bonanza  Creek  is  the  only  stream  between  the  Koyuk  and  the 
Yukon  where  placer  mining  has  been  successfully  carried  on.  This 
creek  is  only  about  a mile  long,  but  values  have  been  found  almost 
the  entire  length  of  its  course,  and,  from  the  character  of  the  gold, 
they  seem  to  be  of  distinctly  local  origin.  Gold  Avas  originally  dis- 
covered and  staked  on  this  creek  in  1899  by  Thomas  Moon  and  his 
partner.  The  absence  of  water  and  the  boom  that  the  Seward  Pen- 
insula placers  were  having  prevented  any  considerable  development 
for  the  first  few  years  on  Bonanza  Creek.  After  the  lower  claims 
had  changed  hands  several  jtimes  they  were  bought  by  the  Nelsons, 
who  have  since  been  the  most  industrious  miners  there.  Other  miners 
have  held  ground  on  No.  2 and  No.  3 above  the  Discovery  claim,  and 
some  work  has  been  done  for  the  last  two  or  three  years.  It  is  hard 
to  realize  that  during  the  boom  days  of  this  camp  nearly  a hundred 
men  rushed  to  the  creek,  and  several  road  houses  and  three  or  four 
saloons  were  in  operation,  for  now  the  creek  is  practically  deserted, 
and  only  four  or  five  white  men  are  living  there. 

a Spurr,  J.  E.,  Reconnaissance  in  southwestern  Alaska  in  1898  : Twentieth  Ann.  Kept. 
U.  S.  Geol.  Survey,  pt.  7,  1900,  p.  261. 

b It  is  extremely  doubtful  if  the  intrusives  of  the  Tordrillo  Mountains  are  post-Cre- 
taceous.  as  the  sedimentary  rocks  they  cut  are  Jurassic  or  older. 


106  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

At  first  the  creek  claims  were  the  ones  from  which  the  values  were 
obtained.  On  the  lower  claim  the  pay  streak  was  400  feet  wide,  but 
it  narrowed  upstream  and  at  the  northern  line  of  No.  1 above  Discov- 
ery the  width  was  only  about  75  feet.  The  gravels  are  typically 
river  wash  in  form  and  consist  of  material  from  near-by  rocks, 
although  some  of  the  pebbles  were  undoubtedly  derived  from  higher 
level  gravels  which  were  not  of  local  origin.  Bed  rock  is  a much  shat- 
tered black  slate  or  shale,  on  the  whole  rather  thinly  laminated  and 
not  so  quartzose  as  the  black  quartzitic  slates  of  the  Paleozoic  sec- 
tion. The  slates  are  cut  by  igneous  rocks  of  the  granite  family. 
An  exposure  of  one  of  the  intrusive  dikes  occurs  a short  distance  north 
of  the  cabins  at  the  junction  of  Bonanza  Creek  and  the  Ungalik. 
Here  the  dike  is  apparently  about  10  feet  wide  and  shows  by  its 
undeformed  character  that  it  was  injected  subsequent  to  the  period 
of  folding  and  faulting  of  the  slates.  It  trends  obliquely  to  the 
slates,  having  a strike  of  N.  5°  E.  and  stands  vertical.  It  is  heavily 
iron  stained  in  places.  This  iron  is  probably  derived  from  the  decom- 
position of  sulphides,  some  of  the  unaltered  material  showing  pyrite 
in  microscopic  sections. 

Above  the  stream  on  the  northeast  side  of  the  valley  is  a bench  on 
which  gravels  have  been  found  that  are  highly  auriferous.  After 
the  exhaustion  of  the  creek  gravels  attention  was  turned  to  this  high- 
level  ground,  and  satisfactory  returns  have  been  obtained  from  it. 
Aneroid  readings  give  the  elevation  of  the  bench  as  about  80  feet 
above  Bonanza  Creek  at  the  cabins,  but  some  gravels  have  been  found 
up  to  an  elevation  of  150  feet  above  the  stream.  The  gold  on  the 
benches  is  medium  coarse  and  of  a dark  reddish  color.  None  of  it  is 
black  gold.  Several  nuggets  were  seen  that  had  small  pieces  of 
quartz  attached.  From  the  owners  it  was  learned  that  the  largest 
nugget  taken  from  this  creek  was  worth  about  $21.  The  value  of 
the  gold  is  high — that  from  the  lower  claim  being  reported  as  worth 
about  $19.25  an  ounce,  and  some  from  higher  up  on  the  creek  and  not 
from  bench  ground  assaying  from  $19.05  to  $19.15  an  ounce. 

Concentrates  from  the  bench  ground  show  a good  deal  of  magnetite 
or  black  sand.  Some  of  the  fragments  of  this  mineral  were  as  much 
as  one-fourth  of  an  inch  in  length.  Together  with  the  magnetite  is 
also  ilmenite  or  the  oxide  of  titanium  and  iron,  which  is  nonmagnetic. 
Garnet  or  the  so-called  “ ruby  ” sand  is  practically  absent  in  all 
parts  of  the  creek.  This  wTas  to  be  expected,  for  none  of  the  rocks  in 
the  neighborhood  show  any  such  development  of  this  mineral  as  is 
the  case  in  the  Seward  Peninsula  placers.  Some  float  pieces  of  anti- 
mony are  occasionally  found  in  the  gravels  of  Bonanza  Creek. 

Bonanza  Creek  has  such  a small  supply  of  water  that  the  extrac- 
tion of  the  gold  from  the  gravels  has  been  a serious  problem.  In 
the  early  days  the  separation  was  accomplished  by  the  use  of  rockers, 


NORTON  BAY-NULATO  REGION,  ALASKA. 


107. 


and  even  during  the  summer  of  1900  this  method  was  still  in  use 
on  some  of  the  creek  gravels  half  a mile  or  so  above  the  mouth  of 
the  stream.  The  discovery  of  gold  in  the  high  benches  called  for  a 
supply  of  water  at  considerable  elevation.  Ditches  except  of  such 
length  as  to  be  prohibitive  in  cost  were  not  feasible,  and  the  experi- 
ment of  pumping  water  from  Ungalik  Kiver  was  resorted  to.  Wood 
cut  in  the  neighborhood  of  the  mines  was  used  for  fuel.  Although 
no  figures  are  available  as  to  the  cost  of  the  water  delivered  on  the 
ground,  it  seems  that  the  fact  that  this  method  was  pursued  until  the 
claims  were  worked  out  is  sufficient  proof  that  the  owners  were  satis- 
fied with  the  project. 

The  method  of  work  was  to  make  cuts  at  intervals  at  right  angles 
to  the  trend  of  the  old  channel.  In  these  trenches  sluice  boxes  were 
placed  in  such  manner  that  their  lower  end  discharged  toward 
Bonanza  Creek.  The  abrupt  cliff  that  occurs  at  the  edge  of  the 
bench  deposit  offered  particularly  favorable  topography  for  the  dis- 
charge of  tailings  on  the  lower  ground  so  that  the  boxes  would  not 
become  choked,  and  this  was  taken  advantage  of.  The  water  pumped 
in  two  lifts  was  delivered  to  the  nozzles  on  the  bench  ground  and  the 
gravels  and  overburden  were  washed  through  the  sluice  boxes.  After 
the  gravels  had  thus  been  sluiced  off,  the  bed  rock  was  taken  up  by 
hand  and  cleaned.  In  places  three  feet  of  the  rather  angular  blocky 
slate  had  to  be  picked  up  to  recover  the  pay  values,  but  over  much  of  the 
bench  ground  it  Avas  necessary  to  take  up  only  from  12  to  18  inches. 

During  1909  the  last  of  the  bench  and  creek  ground  nearest  the 
mouth  of  the  creek  was  exhausted,  and  the  boiler  and  pump  wTere  dis- 
mantled and  put  into  condition  to  be  shipped  away ; the  lower  claims 
may  noAv  be  regarded  as  worked  out.  Good  bench  placer  ground, 
however,  continued  from  the  end  line  of  the  claim,  and  the  next 
upstream  claim  undoubtedly  contains  valuable  deposits.  During  the 
early  part  of  1909  the  OAvner  of  this  ground  Avas  engaged  in  building 
a small  ditch  from  the  upper  part  of  Bonanza  Creek  to  bring  water 
to  this  bench.  The  small  amount  of  Avater  available,  however,  makes 
it  probable  that  the  operations  will  be  much  hampered.  The  bench 
ground  is  frozen,  and  either  a strong  head  of  Avater  will  be  required 
to  break  doAvn  the  gravels  or  else  the  OAvners  will  be  forced  to  resort 
to  thawing. 

On  the  fourth  claim  above  the  mouth  of  Bonanza  Creek  little 
work  was  accomplished  during  1909  and  that  mainly  of  a prospecting 
character.  The  unusually  dry  season  made  this  part  of  the  stream 
practically  dry  by  the  middle  of  July,  and  the  only  gold  taken  out 
was  by  means  of  rockers.  At  this  place  specimens  of  gold  in  a black 
graphitic  slate  were  seen.  This  occurrence  suggests  that  the  carbon, 
which  is  abundant  in  the  slates,  may  have  been  effective  in  causing  the 
deposition  of  the  gold. 


108 


KECONNAISSANCE  IN  SEWAKD  PENINSULA  AND 


At  the  mouth  of  Bonanza  Creek  some  gold  has  been  found  in  the 
gravels  of  Ungalik  River.  Several  rather  shallow  holes  have  been 
put  down  in  the  river  flats,  a few  score  yards  north  of  the  mouth  of 
Bonanza  Creek,  and  good  prospects  have  been  reported.  On  the 
whole,  however,  the  tenor  of  the  gravels  of  Ungalik  River  is  low,  and, 
although  occasional  5-cent  pans  have  been  found,  the  average  indi- 
cated is  so  low  that  the  ground  could  not  be  worked  without  labor- 
saving  devices  capable  of  handling  large  quantities  of  gravel  at  a 
low  cost.  The  gold  is  reported  to  be  irregularly  distributed;  rich 
pockets  separated  by  intervals  of  barren  ground  are  to  be  expected, 
which  condition  is  not  one  calculated  to  encourage  the  development  of 
large  undertakings. 

The-.-other  placer  where  post-Cretaceous  mineralization  apparently 
associated  w7ith  igneous  intrusions  has  been  reported  is  at  Christmas 
Mountain.  Scores  of  lode  claims  have  been  staked  on  this  mountain, 
but,  with  the  exception  of  a little  sulphide  mineralization,  few  indi- 
cations of  profitable  veins  have  been  disclosed.  In  spite  of  the  ap- 
parent absence  of  lodes  that  would  warrant  extensive  development 
it  is  believed  that  there  is  a disseminated  mineralization  in  the 
vicinity  of  this  mountain  that  might  justify  search  for  placers  in  the 
neighborhood.  From  the  reports  of  prospectors  it  was  learned  that 
colors  of  gold  had  been  found  in  the  gravels  of  many  of  the  streams 
heading  in  this  mountain  and  draining  either  into  the  Ungalik  or 
the  Shaktolik.  Several  placer  claims  have  been  staked  on  Christmas 
Creek,  which  enters  the  Ungalik  3 to  4 miles  north  of  camp  A16,  but 
no  mining  has  been  done.  It  seems  probable  that  the  inaccessibility 
of  the  region  would  make  it  unprofitable  to  work  any  but  a rather 
high  grade  placer  at  the  present  time  at  this  place. 

It  is  further  reported  that  stibnite  (antimony  sulphide)  float  has 
been  found  on  the  divide  between  the  Shaktolik  and  the  Ungalik, 
about  4 miles  northeast  of  Bonanza  Creek,  on  the  slopes  of  Christmas 
Mountain.  This  mineral  was  not  found  at  this  place  by  the  Survey 
party.  Its  presence  would  indicate  that  there  has  been  a good  deal 
of  mineralization  and  would  show  that  the  sulphide  mineralization 
already  noted  may  have  introduced  many  different  minerals. 

In  the  same  general  region,  but  not  definitely  associated  with  in- 
trusive igneous  rocks,  are  streams  that  are  said  to  have  some  aurifer- 
ous gravels;  the  geology  of  these  places  is  too  indeterminate  at  the 
present  time,  however,  to  warrant  even  a suggestion  of  the  origin  of 
the  valuable  minerals  contained.  Garryowen  Creek,  a tributary  of 
the  Inglutalik  heading  in  the  Ungalik  divide,  is  reported  to  yield  colors 
of  gold.  Negromoon  Creek,  which  joins  the  Inglutalik  from  the  west 
upstream  from  Garryowen,  also  shows  gold-bearing  gravels.  The 
values,  however,  on  both  these  streams  are  so  low  that  they  are  of 
no  commercial  significance  at  the  present  time  and  can  not  be  worked 


NORTON  BAY-NULATO  REGION,  ALASKA. 


109 


under  existing  conditions.  No  adequate  prospecting  lias  been  done 
on  any  of  these  streams,  and  it  is  therefore  impossible  to  make  even 
an  approximation  of  the  tenor  of  the  gravels. 

GOLD  PLACERS  IN  AREAS  OF  METAMORPHIC  ROCKS. 

DISTRIBUTION. 

As  the  metamorphic  rocks  are  older  than  the  nonmetamorphic  rocks 
they  have  been  subjected,  broadly  speaking,  to  at  least  the  same  num- 
ber of  periods  of  mineralization  as  the  latter  plus  whatever  number 
occurred  before  the  laying  down  of  the  Cretaceous  sediments.  It 
is,  of  course,  realized  that  mineralization  may  be  distinctly  local  and 
may  affect  one  region  and  not  another,  and  it  is  not  intended  to  assert 
that  the  richness  of  a region  is  necessarily  dependent  upon  the  num- 
ber of  periods  of  mineralization  it  has  undergone,  although,  according 
to  the  law  of  chances,  such  a generalization  is  sound.  This  view 
receives  corroborative  support  from  the  field  evidence,  for  in  most 
of  the  Seward  Peninsula  placer  regions  there  were  at  least  two  periods 
of  vein  formation,  during  each  of  which  gold  lodes  were  made,  whereas 
in  the  area  of  unmetamorphosed  sediments  only  one  period  has  been 
recognized. 

Valuable  gold  deposits  have  been  mined  most  extensively  in  Seward 
Peninsula  where  the  metamorphic  rocks  are  most  abundant,  and  it 
is  believed  that  regions  underlain  by  them  are  the  most  promising 
areas  in  which  to  prospect  for  new  placers.  In  general,  the  richest 
placer  areas  are  near  the  contacts  between  the  heavy  overlying  older 
limestones  and  the  underlying  quartz  chlorite  schists.  So  far  as 
known,  the  intrusive  igneous  rocks  older  than  the  Cretaceous  are  not 
auriferous,  and  neither  are  the  more  recent  lava  flows.  Therefore, 
areas  deriving  their  surficial  deposits  from  such  rocks  are  not  likely 
to  afford  valuable  placers. 

Several  of  the  various  placer  camps  located  within  the  area  covered 
by  the  map  of  southeastern  Seward  Peninsula  were  not  visited  during 
1909.  It  has  been  thought  desirable,  however,  to  summarize  the 
investigations  made  during  previous  years  in  order  to  gain  a more 
comprehensive  idea  of  the  mineral  industry  as  a whole,  rather  than 
to  omit  districts  so  important  as  Council  and  Bluff  simply  because 
they  have  been  already  described.  Consequently,  to  complete  this 
part  of  the  report  it  is  necessary  to  refer  to  the  published  reports  of 
Brooks,  Moffit,  Collier,  and  others.  In  the  treatment  of  the  gold 
placers  of  the  areas  of  metamorphic  rocks  a geographic  order  will 
be  adopted.  The  placer  deposits  of  a single  river  basin  will  be  treated 
from  the  mouth  toward  the  head  of  the  stream.  The  various  river 
basins  tributary  to  Norton  Sound  will  be  described  from  east  to  west, 


110 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


beginning  with  the  Koyuk,  and  then  will  follow  descriptions  of 
the  various  basins  emptying  into  Kotzebue  Sound  from  Buckland 
River  westward. 

KOYUK  RIVER  BASIN. 

In  the  Koyuk  Basin  no  gold  placers  are  now  being  mined  and  com- 
mercial mining  has  been  done  in  but  few  places  in  the  past.  Colors 
of  gold  have  been  found  on  many  of  the  streams  and  many  attempts 
at  mining  have  been  made  in  the  region,  but  so  far  without  sufficiently 
encouraging  returns  to  keep  a permanent  force  on  any  of  the  streams. 

About  a mile  west  of  camp  BIT,  at  the  mouth  of  the  Koyuk,  there 
is  a black  limy  schist  and  limestone  that  occurs  east  of  a lighter-colored 

schist,  the  dip  of  both  be- 
ing practically  vertical. 
On  the  beach  at  this  place 
and  extending  for  a con- 
siderable distance  both 
east  and  west  are  many 
large  angular  pieces  of 
quartz  float  that  suggest 
vein  material.  Pans  of 
broken-up  material  from 
the  schists  near  this  place 
show  a number  of  very 
small  colors  of  worn  placer 
gold.  From  a prospector 
living  near  the  place  it 
was  learned  that  1-cent 
pans  had  been  found,  but 
the  small  returns  were  not 
sufficiently  encouraging  to  warrant  any  considerable  expenditures  of 
either  time  or  money. 

Alameda  Creek,  a small  tributary  to  the  Koyuk  from  the  west, 
joining  the  river  a short  distance  below  the  mouth  of  East  Fork,  was 
visited  in  the  early  part  of  August.  Although  no  active  work  was 
in  progress  the  problems  that  have  been  raised  by  earlier  prospecting 
are  such  as  to  attract  the  attention  of  the  geologist.  Figure  12  shows 
the  headward  portion  of  this  stream  with  the  location  of  the  dif- 
ferent prospect  holes  that  have  been  sunk.  The  elevations  are  only 
approximate,  as  the  weather  was  so  changeable  that  an  aneroid  was 
of  no  assistance. 

At  locality  9AS109  south  of  Alameda  Creek  a shaft  192  feet  deep 
was  sunk  all  the  way  through  well-rounded,  predominantly  quartz 
gravel.  The  upper  part  of  the  gravel  is  whitish,  with  black  quartz- 
ite pebbles  and  some  glassy  lava;  not  many  pebbles  of  the  latter 


Figure  12.- — Sketch  map  of  Alameda  Creek. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


Ill 


material  were  found.  Midway  in  the  shaft  the  gravels  are  more  yel- 
lowish and  more  iron  stained  than  in  the  upper  part.  In  the  lower 
part  of  the  hole  the  fine  material  is  of  a greenish-white  color  but  is 
otherwise  similar  to  that  above.  On  reaching  a depth  of  192  feet 
the  miners  were  forced  to  abandon  the  shaft,  as  they  encountered  a 
great  deal  of  water.  This  condition  suggests  that  they  were  ap- 
proaching bed  rock.  This  conclusion  receives  some  support  from  the 
fact  that  in  the  bottom  of  the  shaft  pieces  of  ancient  lava,  probably 
the  country  rock  here,  became  more  numerous. 

It  is  reported  that  in  the  general  gravel  section  cut  by  the  shaft  a 
few  thin  sedimentary  layers  were  found  that  gave  fairly  good  pros- 
pects. A pan  of  the  gravel  from  the  dump  which  was  said  to  have 
come  from  near  the  top  of  the  shaft  gave  two  small  colors.  Samples 
from  the  gravels  said  to  be  near  the  bottom  of  the  shaft  showed  also 
minute  specks  of  gold.  In  the  concentrates  from  the  same  part  of 
the  section  there  was  a good  deal  of  black  sand,  but  garnet  was  prac- 
tically absent.  A good  many  pieces  of  undecomposed  sulphides  were 
also  recognized  in  the  concentrates.  Within  100  feet  of  the  shaft 
a pan  from  the  surface  gravels  directly  under  the  grass  roots  showed 
several  bright  colors  of  gold,  some  magnetite  sand,  and  ilmenite. 

Nearly  due  east  of  the  last  locality  and  at  an  elevation  about  100 
feet  higher  another  shaft  has  been  sunk  (locality  9AS112).  The 
depth  of  the  shaft  is  somewhat  over  TO  feet  and  it  has  not  reached 
bed  rock.  The  material  on  the  dump  consisted  mainly  of  well- 
washed  white  quartz  gravel,  with  some  pebbles  of  black  quartzite 
and  red  lava.  Twenty-five  feet  east  of  this  hole  and  at  a slightly 
higher  elevation  a shaft  had  been  sunk  45  feet  without  reaching  bed 
rock.  The  material  on  the  dump  at  this  shaft  was  more  sandy  and 
the  pebbles  were  smaller  than  at  the  shaft  at  locality  9AS112. 

Northward  down  the  slope  at  locality  9AS113  another  shallow 
shaft  has  been  put  down.  It  was  only  about  15  to  20  feet  deep,  and 
in  it  no  gravel  at  all  was  reported. 

On  a low  bench  on  the  south  side  of  Alameda  Creek,  at  an  eleva- 
tion of  less  than  10  feet  above  the  water,  there  is  a caved  shaft  (locality 
9AS110).  This  was  originally  32  feet  deep  and  reached  bed  rock, 
which  belonged  to  the  group  of  ancient  igneous  rocks.  There  was 
a great  deal  of  well-rounded  quartz  gravel,  but  as  a whole  the  mate- 
rial on  the  dump  was  much  darker  than  at  locality  9AS109,  and 
there  was  a much  greater  proportion  of  lava  fragments.  The  pros- 
pectors who  sunk  this  shaft  reported  that  the  values  were  found 
entirely  on  bed  rock  and  that  the  lower  gravel  went  about  1 cent  to 
the  pan.  Upstream  from  this  shaft  the  present  gravels  of  Alameda 
Creek  are  reported  to  carry  no  gold,  whereas  northeast,  or  down- 
stream, the  creek  gravels  yield  about  7 cents  to  the  10-pan  bucket. 
A mile  and  a half  downstream,  however,  even  this  amount  of  gold 


112 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


disappears  and  the  gravels  are  barren.  From  these  facts  it  would 
appear  that  the  present  creek  may  derive  its  gold  from  the  earlier 
channel.  It  should  be  remembered,  however,  that  if  the  values  occur 
mainly  on  bed  rock  in  this  channel  the  bottom  is  still  below  the  level 
of  Alameda  Creek,  and  therefore  the  reconcentration  has  not  affected 
the  richest  portion  of  the  old  channel. 

Directly  across  the  creek  and  at  the  same  elevation  above  the  stream 
as  locality  9AS110  a shaft  12  feet  deep  has  been  sunk  to  bed  rock. 
The  bed  rock  at  this  place  also  was  dark,  much  fractured,  fine-grained 
lava.  A pan  of  gravel  from  the  dump  at  this  place  showed  an 
abundance  of  green  lava  sand  with  numerous  hornblende  crystals. 
Several  well-rounded  garnets  were  also  noted. 

A mile  and  a half  west  of  this  shaft  and  on  one  of  the  small  tribu- 
taries of  Kenwood  Creek  some  further  prospecting  has  been  done  to 
try  to  locate  the  northwest  continuation  of  the  old  channel.  At 
locality  9AS111  there  is  a shaft  24  feet  deep,  now  badly  caved.  The 
material  on  the  dump  is  nearly  all  angular,  almost  completely  de- 
composed rock,  which  seems  to  contain  some  rounded  black  pebbles. 
The  material  is  so  badly  changed  that  it  is  impossible  to  assert  defi- 
nitely whether  it  represents  a recent  slightly  consolidated  gravel  or 
a more  ancient  sandstone  or  fine  grit.  It  was  claimed  by  the  pros- 
joectors  that  bed  rock  was  reached  in  this  shaft  and  samples  of  the 
material  supposed  to  be  from  the  bottom  of  the  hole  showed  thin 
quartz  and  calcite  veins  with  decomposed  material  between.  Some  of 
the  quartz  was  much  slickensided. 

Forty-five  and  sixty-five  paces  west  of  locality  9AS111  were  two 
other  prospect  pits  at  a slightly  lower  elevation  than  the  one  last 
described.  The  western  one  showed  undoubted  gravel  on  the  dump, 
some  of  the  pebbles  being  3 to  4 inches  in  diameter.  There  were 
very  few  white  quartz  pebbles,  the  greater  number  being  of  black 
quartzite.  There  seems  to  be  little  room  to  doubt  that  this  is  a por- 
tion of  the  same  deposit  encountered  in  the  deep  shaft  at  locality 
9 AS  109.  It  is  unfortunate  that  the  depth  to  bed  rock  has  not  been 
determined  at  the  two  places,  for  it  might  afford  information  either 
as  to  the  direction  of  the  old  drainage  or  as  to  the  amount  of  de- 
formation since  the  cutting  of  the  channel. 

On  the  broadly  open  saddle,  1J  miles  southwest  of  locality  9AS109, 
quartz  gravel  is  reported  to  be  abundant,  and  it  is  believed  that  this 
low  pass  may  mark  the  southern  continuation  of  this  channel.  On 
this  assumption  a party  of  three  or  four  men  was  engaged  in  pros- 
pecting during  the  winter  of  1909-10.  From  a recent  letter  it  seems 
that  little  was  accomplished  at  this  place  during  the  winter,  and 
although  seven  holes  from  18  to  24  feet  deep  were  sunk  their  location 
is  not  sufficiently  explicit  to  show  the  relation  to  the  surrounding 
topography.  It  was  stated,  however,  that  they  found  but  little  of 
the  well-rounded  wash  noted  at  locality  9AS109.  In  several  of  these 


113 


NORTON  BAY-NULATO  REGION,  ALASKA. 

holes  colors  of  gold  were  found,  but  apparently  not  enough  to  war- 
rant further  prospecting.  It  should  be  pointed  out,  however,  that 
even  if  this  be  the  old  course  of  the  valley  it  does  not  follow  that  the 
gravels  will  be  commercially  valuable,  for,  as  has  already  been  noted, 
so  far  as  prospected  the  gravels  in  the  deep  hole  on  Alameda  Creek 
are  not  sufficiently  gold  bearing  to  be  mined  at  the  present  time. 

Not  enough  facts  are  yet  available  for  more  than  a tentative  inter- 
pretation of  the  conditions  under  which  the  old  channel  was  formed. 
It  is  evident  from  the  presence  of  lava  in  the  gravels  of  the  channel 
filling  that  the  channel  was  carved  and  occupied  by  a stream  later 
than  the  effusion  of  the  recent  lava.  It  seems  probable  that  a rear- 
rangement of  drainage  may  have  resulted  from  the  extrusion  of  the 
tongue  of  lava  which  occupied  the  low  country  between  Koyuk  and 
Buckland  rivers  and  flowed  down  the  present  Koyuk  Valley  below 
East  Fork.  This  may  have  resulted  in  turning  the  lower  part  of  the 
Koyuk  out  of  its  former  course  and  allowing  it  to  cut  its  gorge. 
After  the  gorge  had  been  eroded,  either  by  change  in  the  relation 
of  the  land  with  respect  to  sea  level  or  by  capturing,  the  old  valley 
was  filled  and  the  stream  was  so  diverted  that  it  took  up  a course 
parallel  with  the  tongue  of  lava  that  flowed  down  the  Koyuk  Valley. 
It  eroded  the  lava,  thus  etching  out  and  uncovering  its  former  valley, 
in  which  it  now  flows. 

In  regard  to  the  origin  of  the  gold  found  in  the  old  valley  gravels 
there  is  some  question.  Alameda  Creek  is  near  the  area  of  meta- 
morphic  rocks,  and  the  presence  of  a great  number  of  pebbles  of  vein 
quartz  in  the  gravels  suggests  that  they  at  least  have  been  derived 
from  the  quartz  stringers  in  this  series.  If  this  vein  quartz  has  been 
derived  from  this  source  there  is  a strong  presumption  that  the  gold 
has  also  come  from  the  same  place.  On  the  other  hand,  it  should 
be  noted  that  there  are  indications  that  some  of  the  ancient  lava 
is  mineralized.  A shallow  prospect  pit  has  been  sunk  on  a ledge  of 
amygdaloidal  trap  outcropping  on  the  divide  between  the  Koyuk  and 
Alameda  Creek  at  A,  on  figure  12.  Assays  made  at  Nome  of  material 
from  this  pit  are  reported  to  have  given  as  high  as  $3.72  in  gold  per 
ton.  The  rock  shows  no  macroscopic  mineralization,  and  considerable 
doubt  is  felt  of  the  accuracy  of  this  determination. 

Kenwood  Creek,  which  enters  the  Koyuk  from  the  south  above 
East  Fork,  has  been  prospected  near  the  head,  as  already  noted,  and 
a little  work  has  been  done  also  on  the  lower  part.  Two  prospectors, 
who  were  reported  to  have  found  good  prospects  at  this  place  several 
years  ago,  went  to  the  lower  part  of  Kenwood  Creek  during  the 
summer  of  1909.  The  low  water  prevented  their  getting  upstream 
far  enough  with  their  boat  and  they  returned.  It  is  probable,  how- 
ever, that  bed  rock  through  the  lower  part  of  the  creek  is  deep  and 
difficulty  with  water  will  be  experienced. 

71469°— Bull.  449—11 8 


114 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


On  Willow  Creek,  which  enters  the  Koyuk  from  the  south  above 
Kenwood  Creek,  there  are  signs  of  former  prospecting,  but  the  stream 
is  now  deserted.  McPherson  says  that  at  the  time  of  his  visit  (1907) 
location  notices  were  seen,  which  showed  that  the  prospecting  had 
been  done  about  five  years  before. 

Peace  Piver  is  one  of  the  northern  tributaries  of  the  Koyuk  west 
of  East  Fork.  About  12  miles  above  the  mouth  it  forks,  and  near 
this  place  some  prospecting  was  done  during  the  winter  of  1908.  Two 
shafts  were  put  down  on  the  east  bank  of  the  river,  but  they  w~ere  so 
badly  caved  that  only  the  upper  3 feet  or  so  was  visible.  This  part 
of  the  section  shows  brown,  irregularly  bedded  sands  of  even  texture, 
having  in  general  a dip  toward  the  wTest — that  is,  toward  the  stream. 
The  material  on  the  dump  is  fairly  well-rounded  river  wash,  consist- 
ing almost  entirely  of  igneous  rocks  with  some  red,  iron-stained  gravel 
of  the  same  nature.  The  eastern  of  the  two  holes  was  probably  not 
more  than  15  feet  deep,  but  the  other  may  have  been  25  feet  deep. 
Some  material  put  aside  as  though  it  were  the  pay  gravel  was  a 
greenish-brown  sand. 

About  100  yards  east  of  this  place  and  on  a slightly  higher  bench 
there  is  another  shaft  now  filled  with  water.  This  pit  was  probably 
not  more  than  5 or  10  feet  deep.  From  the  material  on  the  dump  it 
appeared  that  the  gravel  is  not  so  well  rounded  and  there  is  much 
more  mud  mixed  with  the  sand.  The  upper  2 or  3 feet,  which 
was  the  only  part  visible,  instead  of  consisting  of  sands  as  in  the 
western  holes,  was  entirely  formed  of  muck.  From  prospectors  it 
was  learned  later  in  the  season  that  some  gold  had  been  found  in 
these  holes,  but  not  enough  to  warrant  further  exploitation.  It  was 
currently  reported  that  one  piece  of  gold  found  there  was  worth 
4 cents,  but  this  was  the  largest  piece.  The  presence  of  gold  at  this 
place  suggests  the  possibility  of  some  of  the  ancient  lavas  having 
been  more  or  less  mineralized,  but  the  evidence  is  not  sufficiently 
definite  to  preclude  other  sources  of  origin. 

Mendenhall  notes  that  in  1900  Big  Bar  Creek  had  been  prospected 
and  a mining  district  established  there.  He  was  unable  to  learn  the 
success  of  the  operations,  but  the  fact  that  in  1903,  when  this  region 
was  visited  by  Moffit,  no  work  was  in  progress  and  the  creek  was 
deserted  shows  that  the  gold  tenor  of  the  gravels  must  have  been  too 
low  to  make  mining  profitable. 

A tributary  creek  farther  up  stream  and  heading  in  the  hills  near 
the  low  pass  into  Death  Valley  and  the  upper  part  of  the  Koyuk 
basin  is  mentioned  by  Mendenhall  as  follows : a 

Just  above  the  camp  of  September  5 another  tributary  enters  from  the  south 
carrying  only  schistose  pebbles.  These,  however,  are  very  calcareous.  Most 
of  the  streams  which  enter  the  upper  course  of  the  river  from  the  north  lie 

° Mendenhall,  W.  C.f  op.  cit.,  p.  213. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


115 


without  the  lava  belt,  but  the  schists  here  have  not  the  aspect  of  the  gold- 
bearing  members-  At  Cheenik  in  the  fall  we  met  prospectors  who  had  been  up 
the  river  and  reported  finding  colors  all  along  its  course. 

Moffit  in  1903  reported  no  mining  in  this  part  of  the  river  basin, 
and  no  signs  of  recent  work  were  seen  by  the  party  in  1909. 

KWIK  RIVER  BASIN. 

No  mining  was  in  progress  during  1909  on  any  of  the  streams  in  the 
Kwik  River  basin,  and  so  far  as  could  be  learned  little  or  no  prospect- 
ing has  been  done  in  the  past  in  this  area.  On  the  head  of  Quartz 
Creek,  about  3 or  1 miles  east  of  camp  C3,  there  were  some  old  claim 
stakes  and  some  sluicing  had  been  done  several  years  ago.  McPher- 
son, who  visited  this  region  in  1907,  noted  that  he  found  location 
notices  of  about  five  years  previous  date  on  this  creek. 

TUBUTULIK  RIVER  BASIN. 

During  the  time  that  the  suryey  party  of  1909  was  in  the  vicinity 
of  the  Tubutulik  no  prospectors  were  seen  and  no  evidence  of  any 
recent  mining  was  observed.  Practically  the  only  thing  that  is 
known  about  the  mining  in  the  basin  is  furnished  by  the  report  of 
Mendenhall,®  in  which  the  following  statements  are  made : 

This  stream,  while  farther  from  the  known  productive  districts  than  the 
Fish,  was  the  object  of  considerable  attention  during  the  season  of  1900.  The 
surface  gravels  of  the  river  bars  gave  colors  quite  as  heavy  as  those  on  Fish 
River,  wherever  a pan  was  washed  out — at  least  as  far  up  as  the  granite 
area.  We  had  no  reports  from  the  head  of  this  stream  and  did  not  have  an 
opportunity  to  examine  it  ourselves,  but  the  area  drained  by  it  is  not  par- 
ticularly promising.  Mr.  C.  C.  Alexander  and  members  of  his  party,  who  had 
been  prospecting  on  Chukajak  and  Vulcan  creeks  during  the  fall  of  1899  and 
the  summer  of  1900,  report  the  finding  of  coarse  gold  early  in  their  work  on  the 
former  stream,  but  more  thorough  development  did  not  fulfill  the  promise  of 
this  first  find.  Reports  of  favorable  prospects  here  had,  however,  reached 
Golofnin  Bay  and  Nome,  and  a small  stampede  toward  the  Tubutulik  resulted. 
When  we  left  the  river,  late  in  August,  many  outfits  were  reaching  the  field. 
Reports  toward  the  end  of  September  did  not  tend  to  confirm  the  earlier  ac- 
counts of  rich  strikes  there. 

It  was  reported  that  some  mining  was  done  several  years  ago  on  the 
next  stream  above  Lost  Creek.  According  to  Mendenhall  the  name 
of  this  creek  was  Admiral,  but  the  claims  were  described  as  on  Camp 
Creek.  It  seems  probable  that  the  two  names  are  applied  to  the 
same  stream,  but  which  is  correct  could  not  be  determined.  From 
the  character  of  the  bed  rock  near  this  stream  it  would  appear  that 
the  geology  is  complex  and  that  the  older  schists  form  the  lower  part 
of  the  valleys,  so  that  it  is  presumed  the  gold  was  derived  from  them. 
Placer  mining  on  Camp  Creek  was  carried  on  by  means  of  horse 

“ Mendenhall,  W.  C.,  op.  cit.,  p.  212. 


116  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

scrapers,  but  the  absence  of  any  recent  work  in  the  vicinity  seemed  to 
show  that  the  returns  were  not  satisfactory.  From  the  strong  evi- 
dence of  glaciation  of  the  valley  type  in  many  of  the  streams  head- 
ing in  the  Darby  Range  and  entering  the  Tubutulik  from  the  west 
it  seems  unlikely  that  any  rich  placers  will  be  found  in  that  part  of 
the  basin.  The  eastern  boundary  of  the  basin  in  the  southern  part 
is  formed  of  the  Ungalik  conglomerate  so  that  strong  mineralization 
is  not  to  be  expected  from  it.  Farther  north  the  eastern  part  of  the 
Tubutulik  divide  is  formed  of  the  Paleozoic  limestones,  and  these  are 
not  promising  rocks  from  which  to  derive  placers.  It  is  felt,  there- 
fore, that  a large  part  of  this  drainage  basin  is  not  particularly 
favorable  for  commercially  important  placers. 

KWINIUK  RIVER  BASIN. 

Practically  the  whole  of  Kwiniuk  River  and  its  tributaries  flow  in 
valleys  carved  in  the  igneous  rocks  that  make  up  the  Darby  Range. 
So  far  as  is  known  these  rocks  are  but  slightly  mineralized.  Conse- 
quently there  is  but  little  chance  that  the  detritus  worn  from  these 
rocks  would  form  valuable  placer  deposits.  In  the  lower  part  of 
the  course,  where  the  bed  rock  is  heavily  covered  by  unconsolidated 
deposits,  the  character  of  the  country  rock  is  not  evident,  and  the 
more  mineralized  schists  may  occur.  If  this  is  the  case,  there  is  some 
possibility,  where  concentration  has  been  effective,  that  placers  may 
be  discovered.  The  depths  of  covering  and  the  question  of  handling 
water  would  make  the  development  of  such  placers  difficult. 

FISH  RIVER  BASIN. 

MAIN  STREAM. 

The  main  Fish  River  basin  has  not  been  important  as  a placer  dis- 
trict, although  the  tributaries  of  the  Niukluk,  its  longest  western 
branch,  have  produced  more  gold  than  those  of  all  the  rest  of  the 
region.  The  name  of  the  principal  town,  Council,  will  be  used  to 
designate  this  placer  region  in  order  to  distinguish  it  from  the  rest 
of  the  Fish  River  basin.  According  to  Mendenhall"  Fish  River 
carries  gold  from  its  mouth  to  the  northern  end  of  the  gorge. 
Throughout  the  lower  part  of  the  river  the  colors  are  very  light, 
but  they  become  heavier  in  the  constricted  part  of  the  valley,  where 
the  stream  crosses  the  belt  of  limestones  and  schists.  Opposite  the 
mouth  of  Anaconda  Creek,  as  the  lower  part  of  Pargon  River  is 
called,  pans  taken  from  the  broken  rim  rock  yielded  from  one-half  a 
cent  to  1 cent  each.  According  to  the  same  author  prospectors  found 
nothing  in  the  upper  flats  of  Fish  River,  and  so  far  as  reported  the 
streams  flowing  out  of  the  mountains  to  the  north  do  not  yield  colors. 


a Mendenhall,  W.  C.,  op.  cit.,  p.  212. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


117 


From  the  geologic  description  of  the  northern  and  eastern  part  of 
the  Fish  River  basin  it  is  seen  that  the  rocks  are  schists  and  lime- 
stones, which  appear  to  be  the  same  as  the  rocks  in  some  of  the  placer 
regions,  except  that  the  schists  contain  much  greater  quantities  of 
biotite.  Veins  are  equally  abundant  in  both  types,  and  it  is  believed 
that  the  absence  of  placers  may  be  explained  in  part  by  the  valley 
glaciation  that  has  scoured  out  the  water-sorted  deposits  from  most 
of  the  valleys  heading  in  the  Bendeleben  and  Darby  mountains. 
This  process  has  scattered  the  deposits,  which  may  have  existed  in  the 
valleys  prior  to  this  erosion.  Information  on  the  subject  is  still  too 
meagre  to  allow  a final  judgment  as  to  the  reason  for  the  absence  of 
placers  in  this  part  of  the  basin,  but  it  is  believed  that  the  physical 
history  rather  than  the  lithologic  character  is  responsible  for  the 
apparent  absence  of  placers. 

COUNCIL  REGION. 

Placer  gold  has  long  been  known  in  the  region  around  Council,  for 
it  was  reported  by  members  of  the  Western  Union  Telegraph  Expedi- 
tion in  1865,  and  in  1892  John  Dexter  is  said  to  have  notified  mem- 
bers of  the  silver-lead  mining  company  that  he  had  found  gold  there. 
It  was  not  until  1896-97,  however,  that  the  discovery  of  Ophir  Creek, 
the  richest  one  in  the  Council  district,  was  made  by  Mordant,  Mel- 
sing,  Libby,  and  Nelson.  Although,  apparently,  gold  was  found  at 
that  time,  it  was  not  until  the  spring  of  1898  that  the  district  was 
organized  and  active  placer  mining  begun.  So  valuable  have  the 
placers  turned  out  that  in  1908  Collier  estimated  that  the  gold  output 
up  to  that  year  was  between  $5,000,000  and  $6,000,000.®  Since  that 
time  $2,000,000  to  $3,000,000  more  has  been  taken  out,  so  that  this 
camp  has  been  second  in  production  to  that  of  Nome. 

The  productive  creeks  in  this  so-called  Council  region  from  south- 
east to  west  are  Fox,  Mystery,  Melsing,  Ophir,  Goldbottom,  Camp,  and 
Elkhorn  creeks.  All  except  Fox  Creek  are  tributaries  of  the  Niukluk, 
and  Fox  Creek  joins  Fish  River  less  than  4 miles  below  the  Niukluk. 

Fox  Creek  has  never  been  a rich  creek.  The  only  valuable  ground 
was  on  a small  tributary  known  as  I.  X.  L.  Gulch,  and  on  the  main 
valley  at  the  mouth  of  this  stream.  At  this  place,  according  to 
Collier,6  about  2 ounces  of  gold  were  taken  from  about  4 cubic  yards 
of  pay  dirt.  A little  prospecting  has  been  done  here  in  every  year 
since  1906,  but  the  production  is  practical^  negligible. 

Collier®  reported  that  on  Mystery  Creek,  1 mile  from  its  mouth, 
$6  to  $8  nuggets  have  been  found.  Part  of  the  gold  was  bright  and 

a Collier,  A.  J.,  and  others,  The  gold  placers  of  parts  of  Seward  Peninsula,  Alaska  : 
Bull.  U.  S.  Geol.  Survey  No.  328,  1908,  p.  236. 

b Idem,  pp.  237-238. 

c Idem,  p.  240. 


118 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


part  was  rusty,  but  all  is  rough  and  angular  as  though  derived  from 
near-by  sources.  On  Mud  Creek,  a small  side  stream  from  the  wTest, 
one  claim  was  operated  in  1903.  The  gold  here,  according  to  Collier, 
is  found  both  in  the  gravel  and  to  a depth  of  3 or  4 feet  in  crevices 
of  the  bed  rock.  It  is  very  rough,  spongy,  and  somewhat  rusty,  and 
is  coarse  and  easily  saved.  Near  the  mouth  of  Mystery  Creek  a hole 
102  feet  deep  was  sunk,  but  no  values  were  found.  In  1907  and  for 
the  succeeding  two  years  there  has  been  mining  on  this  creek,  but 
the  production  was  small  though  the  returns  were  commensurate  with 
the  amount  of  time  spent. 

Melsing  Creek  was  one  of  the  first  creeks  on  which  gold  was  dis- 
covered, and  it  has  been  a constant  though  small  producer  ever  since. 
According  to  the  1900  report,  40  men  were  engaged  on  the  creek. 
Collier  estimates  that  up  to  1904  about  $50,000  had  been  taken  from 
this  stream.  The  auriferous  gravels  seem  to  occur  only  below  the 
mouth  of  Basin  Creek.  From  this  part  of  the  creek  the  small  pieces 
of  gold  are  reported  to  be  nearly  all  smooth  and  bright,  whereas  the 
larger  ones  are  rusty.  Richest  concentration  occurs  on  a clay  layer. 
At  the  mouth  of  Basin  Creek  the  gold  is  found  throughout  the 
gravel,  but  is  most  abundant  on  and  in  bed  rock.  Collier  states  that 
the  average  yield  per  man  per  day  in  1903  was  about  $50.®  One  of 
the  nuggets  examined  by  him  from  this  claim  showed  a small,  square 
hole  filled  with  hydrous  iron  oxide,  probably  the  mould  of  a pyrite 
crystal' associated  with  the  gold. 

In  1906  there  had  been  four  parties  of  3 to  10  men  each  on  Melsing 
Creek  below  Basin  Creek.  In  1907  a steam  scraper  was  built  at 
the  mouth  of  Melsing  Creek,  but  delays  in  building  prevented  its 
running  full  time.  Work  still  continued  near  the  mouth  of  Basin 
Creek  and  a short  distance  down  stream.  During  1908  and  1909 
work  was  continued  on  about  the  same  scale  and  at  the  same  places 
as  in  the  past,  and,  in  addition,  during  the  last-mentioned  year,  some 
mining  was  done  on  the  lower  part  of  Basin  Creek.  The  operations 
were,  however,  on  a small  scale  and  the  production  was  slight. 

Ophir  Creek  is  the  most  important  gold  producer  in  the  Council 
region.  By  1903,  according  to  Collier,  the  entire  creek  had  been 
prospected,  and  during  that  year  1,000  men  were  at  work  on  the  main 
stream  and  its  tributaries.  Gradually  the  number  of  men  employed 
has  decreased,  but  this  has  been  due  in  part  to  the  replacement  of 
hand  labor  by  mining  machinery.  Some  mining  was  done  in  1903 
at  the  mouth  of  this  stream  in  the  Niukluk  River  flats.  These  gravels 
are  estimated  to  carry  from  50  cents  to  $1  a yard  in  bright,  nearly 
flour,  gold.  Concentrates  show  much  magnetite  and  garnet,  with 
smaller  quantities  of  pyrite  and  ilmenite.  This  deposit  was  developed 


° Idem,  p.  242. 


NORTON  BAY-NtTLATO  REGION,  ALASKA. 


119 


by  a steam  dredge  with  an  estimated  capacity  of  about  3,000  cubic 
yards  per  day.  Bed  rock  is  rather  deep  and  the  difficulty  of  handling 
the  water  makes  mining  expensive.  According  to  Collier,  the  gold 
has  been  derived  not  only  from  Ophir  Creek,  but  also  from  the  other 
streams. 

Farther  up  Ophir  Creek  the  gold  becomes  coarser  and  the  values 
per  cubic  yard  are  higher.  After  a short  experiment  on  the  ground 
near  the  mouth  of  Ophir  Creek  already  described  the  dredge  was 
moved  upstream  and  has  been  in  successful  operation  ever  since.  In 
an  account  of  this  dredge  recently  published  by  Rickard  ° it  is 
shown  that  the  average  cost  is  32  cents  a yard  and  the  average  gold 
tenor  of  the  gravels  worked  is  84  cents  a yard.  The  low  value  per 
yard  is  in  part  due  to  the  fact  that  some  of  the  ground  had  been 
worked  before  by  more  primitive  methods. 

Next  upstream  on  Ophir  Creek  from  the  dredge,  hydraulic  mining 
has  been  tried  and  some  good  placer  has  been  uncovered.  The 
ground  mined  is  now  mainly  on  a low  bench,  but  in  the  past  the 
creek  gravels  have  been  worked  by  pick-and-shovel  methods  with 
satisfactory  results.  Still  farther  upstream  and  only  a short  dis- 
tance below  Sweetcake  Creek  is  the  Discovery  claim.  It  has  been 
worked  for  several  years  but  was  finally  exhausted  by  the  use  of 
hydraulic  elevators.  The  values  were  in  fairly  coarse  gold  of  a 
bright  color.  This  claim  was  probably  the  second  richest  on  the 
entire  creek  and  it  is  reported  that  $1,000,000  was  taken  from  it. 

Sweetcake  Creek  was  staked  in  1898  and  was  the  scene  of  probably 
the  first  successful  placer  mining  in  the  precinct,  it  being  reported  b 
that  $36,000  were  taken  from  one  claim  that  year.  The  only  produc- 
tive claims  are  on  the  lower  part  of  this  stream;  they  were  notable 
contributors  in  the  early  days  of  the  camp,  although  since  1903  little 
gold  has  been  won  from  them.  Some  of  the  gold  was  angular  and 
showed  quartz  attached. 

Little  of  value  has  been  found  on  the  main  stream  for  nearly  1 
mile  above  Sweetcake  Creek.  At  this  place,  however,  there  is  creek 
and  bench  ground  that  has  been  very  rich.  Pick-and-shovel  methods 
were  used  even  in  the  early  days  and  in  1907  an  unsuccessful  attempt 
was  made  to  use  a dry-land  dredge,  which  was  followed  by  the  suc- 
cessful use  of  a derrick  and  horse  scrapers.  The  pay  streak  in  the 
creek  was  from  100  to  200  feet  wide.  The  bench  gravel  near  this 
place,  according  to  Collier,  was  not  well  sorted.0  The  pay  streak 
is  said  to  run  10  to  15  cents  a pan.  One  nugget  worth  $3.75  is  re- 
ported by  Collier  to  have  been  found  here,  but  nearly  all  the  gold  is 
fine  and  flaky. 

“ Rickard,  T.  A.,  Dredging  on  Seward  Peninsula  : Min.  and  Sci.  Press,  vol.  97,  1908, 
pp.  234-240. 

6 Collier,  A.  J.,  and  others,  op.  cit.,  pp.  250-251. 

0 Idem,  p.  245. 


120  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

From  this  place  nearly  to  the  mouth  of  Dutch  Creek  the  Ophir 
Creek  gravels  and  benches  have  yielded  probably  nearly  $750,000  in 
gold.  In  the  central  portion  of  this  part  of  the  valley  the  presence 
of  limestone  bedrock  allows  a large  portion  of  the  water  to  flow  in 
subterranean  channels  and  it  is  notable  that  the  quantity  of  gold  in 
the  gravels  decreases  also.  At  the  mouth  of  Dutch  Creek  the  richest 
claim  in  the  whole  Ophir  Creek  basin  was  located,  and,  although  now 
exhausted,  this  claim  and  the  claim  next  below  probably  produced 
nearly  a quarter  of  the  gold  won  in  the  entire  Council  region.  Much 
of  the  gold  seems  to  have  been  of  local  origin,  as  pieces  with  quartz 
attached  were  by  no  means  uncommon.  On  Dutch  Creek  little  has 
been  done  and  then  only  on  the  lower  claims  adjacent  to  Ophir 
Creek.  Values  are  reported  both  in  the  creek  and  bench  gravels. 

Above  Dutch  Creek  the  values  in  Ophir  Creek  suddenly  decrease 
and  then  gradually  increase  toward  the  northwest  to  within  a mile 
or  so  of  Crooked  Creek.  All  of  the  claims  between  these  two  side 
streams  have  been  mined  to  some  extent.  A mile  and  a half  above 
Dutch  Creek,  according  to  Collier,®  excavations  show  from  5 to  14 
feet  of  gold-bearing  gravel  resting  upon  broken  limestone  bedrock, 
and  three-fourths  of  a mile  to  the  north  6 feet  of  sand  and  muck  rest 
upon  about  12  feet  of  gravel  of  which  the  upper  2 or  3 feet  canry  very 
little  gold. 

In  1903  the  only  other  work  done  on  Ophir  Creek  was  near  the 
mouth  of  Crooked  Creek.  “ Here  terrace  gravels  on  the  left  bank 
were  being  exploited.  The  bedrock  of  the  deposit  is  probably  little 
above  the  present  creek.  A section  showed  2 or  3 feet  of  muck  over- 
lying  5 or  6 feet  of  gravel  which  rested  on  calcareous  schist.” 6 No 
Avork  was  in  progress  during  1906,  but  near  this  place  during  1908 
and  1909  a small  dredge  was  installed  and  according  to  local  reports 
was  giving  satisfaction  in  handling  creek  gravels. 

Crooked  Creek  has  been  one  of  the  richest  tributaries  of  Ophir 
Creek.  Collier  noted  that  in  1903  more  men  were  employed  there 
than  on  any  one  of  the  other  side  streams.  Near  the  junction  of  this 
stream  with  Ophir  Creek  the  pay  streak  is  about  250  feet  wide,  but 
it  narrows  rapidly  upstream.  According  to  Collier,®  the  pay  streak 
is  reported  to  have  been  about  6 feet  thick.  The  gold  tenor  of  the 
gravels  mined  is  estimated  at  $4.50  to  the  cubic  yard.  The  gold  is 
comparatively  coarse  and  the  pieces  well  rounded.  Some  are  bright 
and  others  are  iron  stained.  In  the  sluice  boxes  are  found  heavy  con- 
centrates consisting  principally  of  garnet  and  magnetite,  but  includ- 
ing some  topaz.  Above  the  lower  claim  the  pay  streak  is,  in  the  main, 
not  more  than  20  feet  wide  and  the  bedrock  is  a schistose  limestone. 


° Idem,  p.  249. 

b Collier,  A.  J..  and  others,  op.  cit.,  p.  250. 
c Idem,  p.  252. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


121 


Balm  of  Gilead  Gulch,  which  enters  Crooked  Creek  from  the  south- 
west, had  gold  “ from  the  surface  down,  but  is  richest  in  the  crevices 
of  the  limestone.  The  gold  is  rough  and  angular,  with  sharp  cor- 
ners,”® and  is  undoubtedly  of  local  origin.  Albion  Gulch  contains 
auriferous  gravels  throughout  its  course.  In  1907  two  camps  were 
established  on  this  stream,  and  a rich  hillside  placer  was  mined  by 
hydraulicking.  The  difficulty  of  obtaining  an  adequate  constant  sup- 
ply of  water  has  much  hampered  developments  on  both  of  these 
gulches. 

Above  Crooked  Creek  the  valley  of  Ophir  Creek  has  been  pros- 
pected, but  little  actual  mining  has  been  done.  Near  the  upper  end 
of  the  canyon  of  Ophir  Creek  there  is  a little  bench  gravel,  which 
was  being  developed  at  the  time  Brooks  visited  the  region  in  1903. 
Although  this  work  may  have  yielded  wages,  it  was  not  highly  remu- 
nerative and  was  soon  abandoned.  Further  prospecting  was  under- 
taken here  in  1907,  but  was  not  successful  in  locating  placer. 

From  the  general  distribution  of  the  values  in  the  Ophir  Creek 
gravels  it  seems  evident  that  many  of  the  rich  placers  of  the  stream 
are  formed  by  the  reconcentration  of  former  bench  deposits.  At 
other  places,  however,  it  seems  clear  that  the  richness  is  due  to  prox- 
imity to  local  mineralization.  Collier  notes  that  a sample  taken  from 
the  schists  adjacent  to  some  quartz  stringers  near  the  mouth  of  Ophir 
Creek  contained  some  gold  and  that  samples  crushed  in  a hand  mortar 
and  panned  yielded  free  gold.  On  Crooked  Creek  there  “ is  a min- 
eralized belt  12  feet  wide,  which  strikes  northwest.  In  this  impreg- 
nated zone  vein  quartz  is  associated  with  pyrite.  It  is  reported  to 
assay  as  high  as  $8  to  the  ton.” 5 Near  this  place  on  the  divide,  be- 
tween Gold  Bottom  and  Crooked  creeks,  there  is  a lode  which  seems 
to  be  similar  to  the  one  previously  noted ; it  is  significant  as  pointing 
to  the  origin  of  some,  at  least,  of  the  Crooked  Creek  gold,  which  is 
very  sharp  and  angular  and  in  many  instances  has  quartz  attached. 
None  of  these  mineralized  veins  have  been  mined,  and  it  is  doubt- 
ful whether  the  diffused  character  of  the  mineralization  would  permit 
economic  treatment.  The  absence  of  valuable  placer  in  the  upper 
part  of  Ophir  Creek,  beyond  the  canyon,  strongly  suggests  that  the 
gold  was  not  derived  from  the  biotite  schists  that  occur  in  the  Bende- 
leben  Mountains. 

Farther  up  the  Niukluk  is  Camp  Creek.  Mining  on  this  stream 
was  described  by  Collier c as  follows : 

Camp  Creek  flows  into  the  Niukluk  from  the  south  about  a mile  below  Gold 
Bottom  Creek.  Several  claims  were  worked  on  this  creek  in  1904.  The  aurifer- 
ous gravel  is  from  50  to  100  feet  wide  and  about  3 feet  thick,  with  an  over- 


" Idem,  p.  254. 

b Collier,  A.  J.,  and  others,  op.  cit.,  p.  252. 
c Idem,  p.  256. 


m 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


burden  of  about  3 feet,  and  is  said  to  carry  from  75  cents  to  $1  a cubic  yard. 
Most  of  the  mining  was  done  by  the  shoveling-in  process,  but  one  claim  was 
hydraulicked. 

Only  a little  desultory  work  has  been  done  on  this  stream  within 
the  last  two  or  three  years. 

The  next  gold-producing  tributary  of  the  Niukluk  from  the  north 
above  Ophir  Creek  is  Goldbottom  Creek,  with  its  tributary,  Warm 
Creek.  Mining  began  on  Warm  Creek  in  1900  and  up  to  1903  the 
basin  is  estimated  to  have  produced  about  $100,000.  “ Most  of  the 

gold  is  rough  and  iron  stained,  and  some  of  it  is  almost  black.  One 
nugget,  worth  $45.10,  at  $16  an  ounce,  was  found  in  1902;  and  one 
worth  $12.33  in  1903.  The  concentrates  contain  ilmenite,  scheelite, 
magnetite,  garnet,  and  some  hematite  and  rutile.”  ° Mining  has  been 
confined  to  the  portion  of  the  stream  near  the  junction  of  Warm  and 
Goldbottom  Creeks,  but  colors  of  gold  have  been  reported  from  many 
parts  of  the  basin.  During  1906  there  was  a little  mining,  but  since 
then  practically  nothing  was  done  until  1909,  when  two  dredges  were 
erected  in  the  lower  part  of  the  valley.  It  was  so  late  before  the 
dredges  were  completed  that  their  production  for  1909  was  slight. 
Mineralization  on  a small  scale  is  recognized  at  many  places,  and  a 
short  distance  upstream  a vein  on  which  some  development  work  has 
been  done  was  found  at  the  contact  of  schist  and  limestone.  “ Near 
the  mouth  of  the  creek  are  two  quartz  veins,  one  about  3 feet  wide  and 
the  other  about  1 foot  wide,  striking  N.  30°  E.  and  standing  nearly 
vertical.” *  6 As  the  pebbles  in  the  placers  all  seem  to  be  of  local  origin, 
it  is  probable  that  the  gold  is  also  derived  from  veins  within  the  basin. 

On  Elkhorn  Creek  mining  began  in  1900  and  was  reported  upon  by 
Richardson0  as  follows: 

Near  the  mouth  of  the  creek  2\  feet  of  gravel  overlie  6 inches  of  clay  and 
disintegrated  bed  rock.  It  is  reported  by  miners  that  the  pay  streak  is  in 
patches  and  that  the  average  yield  of  pans  is  5 cents.  The  bench  near  the 
mouth  gives  colors,  but  has  not  been  developed.  The  bed  rock  is  mica  schist, 
interbedded  with  limestone,  and  the  strike  is  at  right  angles  to  the  course  of  the 
stream,  with  almost  vertical  dips,  giving  favorable  conditions  for  the  concen- 
tration of  gold.  The  gold  is  medium  coarse  and  bright  yellow  in  color.  Some 
very  coarse  gold  has  been  found  stained  with  iron.  The  average  assay  shows 
its  value  to  be  $19.12  an  ounce.  Quartz  is  often  found  attached  to  the  placer 
gold,  and  one  nugget  was  attached  to  a piece  of  mica  schist.  This  goes  to  show 
that  it  is  of  local  origin.  One  nugget  worth  $55  has  been  found,  and  several 
worth  from  $12  to  $16. 

a Idem,  p.  256. 

6 Idem,  p.  255. 

c Brooks,  A.  H.,  and  others,  Reconnaissances  in  the  Cape  Nome  and  Norton  Bay  regions, 
Alaska,  in  1900,  a special  publication  of  the  U.  S.  Geol.  Survey,  1901. 


NORTON  BAY-NULATO  REGION,  ALASKA.  123 

In  1903  this  stream  was  visited  by  Collier,®  who  reported  as  follows 
concerning  mining  developments: 

Since  1900  the  placers  for  about  half  a mile  have  been  entirely  exhausted,  but 
farther  . up  the  creek  work  is  still  (1903)  in  progress  both  in  the  creek  bed  and 
on  the  benches.  It  is  estimated  that  the  total  production  of  the  creek  up  to 
date  (1903)  has  been  from  $110,000  to  $120,000. 

After  1903  very  little  work  was  done  on  this  stream,  and  when  it 
was  visited  in  1906  it  was  practically  abandoned  and  since  that  time 
mining  operations  have  not  been  re- 
sumed. 

BLUFF  REGION. 

The  region  around  Blulf  has  not 
been  visited  by  Survey  geologists 
since  1906,  and  the  following  descrip- 
tions are  taken  from  Brooks’s  report 
of  his  visit  at  that  time.6  In  order 
to  condense  the  account  certain  parts 
have  been  left  out  and  the  arrange- 
ment has  been  changed.  To  connect 
the  retained  portions  words,  phrases, 
and  sentences  have  been  introduced. 

So  many  changes  have  been  made  that 
quotation  marks  have  been  omitted. 

Gold  is  said  to  have  been  found  at 
Daniels  Creek  in  September,  1899,  by 
William  Hunter  and  Frank  Walker. 

Beach  placer  was  soon  after  located 
and  within  less  than  six  months 
$600,000  had  been  taken  from  a strip 
of  land  less  than  1,000  feet  long. 

Meamvliile.  the  two  lowest  claims  on  Q j/2 , mue 

Daniels  Creek  were  opened  and  in  pIGDRE  13.— sketch  map  and  section 
1900  yielded  probably  $200,000  in  of  Daniels  Creek  placers. 

gold.  Most  of  the  production  of  1901-2  came  from  Discovery  Claim, 
at  the  mouth  of  Daniels  Creek.  Meanwhile  gold  had  been  found  on 
Eldorado  and  Ryan  creeks  and  on  Swede  Gulch.  In  1902  a strong 
company  was  organized  and  has  ever  since  been  in  practical  control 
of  the  important  placer  ground.  Figure  13  shows  graphically  many 
of  the  more  important  features  of  the  Daniels  Creek  placers. 

The  placers  are  of  two  types,  beach  placers  and  creek  placers,  the 
former  consisting  of  ancient  and  recent  beaches.  The  alluvial  mate- 

® Collier,  A.  J.,  and  others,  op.  cit.,  p.  257. 

b Brooks,  A.  H.,  The  Bluff  region  (in  The  gold  placers  of  parts  of  Seward  Peninsula, 
Alaska)  : Bull.  U.  S.  Geol.  .Survey  No.  328,  1908,  pp.  283-293. 


124 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


rial  of  the  creeks  is  of  two  general  types,  that  in  which  clay  pre- 
dominates and  that  which  is  chiefly  sand.  In  many  places  no  struc- 
ture can  be  made  out  in  the  clays ; the  bedding  of  the  sands  and  grav- 
els is  of  the  greatest  irregularity,  locally  changing  its  character  every 
few  feet.  The  indications  are  very  strong  that  the  layers  of  clay, 
which  in  general  lie  near  the  bottom  of  the  deposit,  are  formed  almost 
in  place,  whereas  the  sands  and  gravels  appear  to  have  been  laid  down 
in  swiftly  running  water.  Near  the  head  of  the  creek  the  surficial 
deposits  consist  chiefly  of  clay,  but  near  its  mouth  sands  and  gravels 
predominate. 

Little  can  be  said  of  the  distribution  of  pay  gravels.  The  man- 
agers of  the  hydraulic  mine  report  that  in  general  the  clay  carries 
higher  values  than  the  sand  and  gravel.  This  is  very  significant, 
for  it  appears  to  be  established  that  the  sand  and  gravel  have  been 
far  more  concentrated  than  the  clay.  It  would  indicate  a large  gold 
tenor  for  the  rock  from  which  the  clay  has  been  derived.  In  any 
event  there  can  be  no  question  that  the  gold  is  very  near  its  bed-rock 
source,  which  appears  to  be  at  the  contact  of  mica  schist  and 
limestone. 

From  an  examination  of  the  Daniels  Creek  placers  several  facts 
are  evident — first,  the  source  of  the  gold  is  entirely  local;  second, 
where  it  is  richest,  as  in  the  red-clay  deposits,  there  appears  to  have 
been  little  sorting  action  by  water;  third,  the  gold  is  so  intimately 
associated  with  mica  schist  debris  that  most  probably  the  schist  has 
a close  connection  with  its  origin.  It  is  evident  that  the  stream  gradi- 
ents must  have  been  low  during  the  period  of  the  formation  of  the 
clay.  The  area  was  probably  exposed  for  a long  time  to  the  agencies 
of  weathering  and  an  irregularly  pitted  land  surface  was  produced. 
An  uplift  followed,  as  a result  of  which  the  carrying  power  of  the 
streams  wTas  increased  and  the  deposits  of  sand  and  gravel  were  laid 
down.  At  Daniels  Creek  this  uplift  gave  the  former  level  a slight 
tilt  to  the  west,  as  is  shown  by  the  bedding  of  the  gravels.  The  ele- 
vated beach  deposit  appears  to  have  been  formed  prior  to  this  uplift, 
but  it  would  require  a very  detailed  survey  to  establish  this  fact. 
The  presence  of  gold  at  a depth  of  60  feet  near  the  mouth  of  Daniels 
Creek  reported  in  1907  may  indicate  either  a deep  zone  of  weather- 
ing or  a buried  ancient  beach  line.  A subsequent  uplift,  which  prob- 
ably did  not  exceed  8 feet  at  the  coast,  exposed  this  older  beach  in 
part  to  wave  action  and  this  led  to  reconcentration  of  the  gold  in  the 
gravels  of  the  present  beach. 

The  other  creeks  of  the  district  besides  Daniels  Creek  have  been 
but  little  developed,  for  none  of  them  carry  a sluice  head  of  water  ex- 
cept early  in  the  spring  or  during  heavy  rains.  Eventually,  how- 


NORTON  BAY-NULATO  REGION,  ALASKA. 


125 


ever,  they  will  all  be  hydraulicked  with  water  from  the  Topkok  ditch. 
Sluicing  has  been  done  on  about  half  a dozen  claims  on  Eldorado 
Creek,  and  some  work  has  been  done  on  Ryan  and  Little  Anvil  creeks. 
So  far  as  the  scanty  exposures  show,  the  mode  of  occurrence  of  the 
gold  on  these  streams  is  similar  to  that  of  Daniels  Creek,  but  the 
deposits  are  probably  not  so  rich  and  the  auriferous  gravels  not  so 
extensive. 

BUCKLAND  RIVER  BASIN. 


The  only  stream  tributary  to  Buckland  River,  on  which  gold  placer 
has  been  found,  is  Bear  Creek,  which  heads  in  the  ancient  lava  hills 
that  form  the  western  margin  of  the  basin.  The  first  claims  recorded 
on  this  stream  were  located  by  R.  S.  Hoxie,  L.  Tendness,  and  A.  Barr, 
in  August,  1901.  During  1903,  ac- 
cording to  Moffit,0  about  40  men  were 
at  work  on  Bear  Creek  and  its  tribu- 
taries, Sheridan  and  Cub  creeks,  but 
as  only  about  $10,000  in  gold  was  won 
from  this  basin  during  that  year  it  is 
evident  that  the  work  was  not  very 
profitable.  Figure  14  shows  the  loca- 
tion of  the  principal  places  where  au- 
riferous gravels  have  been  found  on 
this  creek. 

Mica  schist  is  said  not  to  be  found  in 
this  creek,  although  mica  does  appear  in 
the  sands  and  gravels,  which  are  composed 
largely  of  eruptive  material,  and  on  some 
of  the  bench  claims  reach  a thickness  of 
20  feet,  with  several  feet  of  muck  over- 
lying.  In  places  on  the  creek  a consid- 
erable quantity  of  a heavy  red  cherty  rock 
remains  in  the  boxes  with  the  gold  and  is 

a source  of  some  annoyance  to  the  miner.  This  is  especially  true  on  Cub  Creek. 
On  Sheridan  and  Bear  creeks  the  gold  is  mostly  on  bed  rock,  differing  in  this 
respect  from  that  on  Cub  Creek,  where  it  is  found  throughout  the  whole  thick- 
ness of  the  2 feet  of  stream  gravel ; on  the  other  hand,  gold  from  Bear  and  Cub 
creeks  is  light  and  flaky,  while  that  from  Sheridan  is  heavy.  All  the  gold  is 
bright  yellow  in  color,  assaying  $19.20  to  the  ounce.  A little  “ white  iron  ” 
pyrite  is  present  and  also  an  abundance  of  black  sand,  which  is  entirely  removed 
by  the  magneto 


Figure  14. — Map  showing  location  of 
placer  camps  on  Bear  Creek. 


From  1903  to  1907  a little  desultory  prospecting  and  mining  was 
done,  but  during  the  latter  year  the  building  of  a ditch  along  the 
west  slope  of  the  valley  revived  interest  in  the  region.  The  small 
precipitation  of  1908,  however,  prevented  any  extensive  use  of  the  new 


® Moffit,  F.  H.,  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska : Bull.  U.  S. 
Geol.  Survey  No.  247,  1905,  p.  64. 

6 Moffit,  F.  H.,  op.  cit.,  p.  64. 


126 


EECONNAISSANCE  IN  SEWAED  PENINSULA  AND 


ditch,  and  in  1909  there  was  no  evidence  that  productive  mining  was 
in  progress. 

In  spite  of  the  small  production  of  gold,  this  region  is  of  interest 
as  indictaing  that  the  placer  has  been  derived  from  the  ancient  lavas 
that  form  the  Buckland  and  Kewalik  divide.  It  will  be  remembered 
that  this  source  of  origin  was  suggested  as  a possibility  for  the  placers 
on  Alameda  Creek  in  the  Koyuk  basin,  which  is  on  the  southern  exten- 
sion of  this  lava  series.  It  should  be  pointed  out,  however,  that 
although  a little  local  mineralization  may  have  affected  this  group 
of  rocks  here  and  there,  so  far  as  can  be  foretold  by  present  indica- 
tions, there  is  slight  chance  of  finding  any  considerable  extent  of 
rich  placer  on  those  streams  where  the  ancient  lavas  form  the  country 
rock.  In  other  words,  it  is  believed  that  only  “ one  man  camps  ” 
will  be  established  on  streams  deriving  their  gravels  from  areas  of 
ancient  lavas. 

KIWALIK  RIVER  BASIN. 

The  main  production  of  Kiwalik  River  comes  from  Candle  Creek 
and  its  tributaries.  As  the  larger  part  of  this  stream  lies  outside 
of  the  ajea  represented  on  the  map  accompanying  this  report  and  as 
the  region  was  not  visited  in  1909  by  the  geologists  of  the  Survey 
party  it  is  desirable  to  omit  any  detailed  description  of  the  placers. 
As  complete  descriptions  as  the  facts  in  hand  warranted  have  already 
been  published  by  the  Survey.®  From  these  reports  it  will  be  learned 
that  the  production  from  Candle  Creek,  on  which  gold  was  dis- 
covered in  1901,  has  amounted  to  about  $2,500,000  in  gold.  During 
the  first  years  of  the  camp  most  of  the  values  came  from  the  creek 
gravels,  but  afterward  high-level  deposits  were  found  which  seem  to 
be  of  a type  intermediate  petween  bench  and  hillside  placers.  As 
these  deposits  are  in  places  deep,  mining  has  been  carried  on  in  winter 
as  well  as  in  summer.  According  to  Moffit  :6 

The  gold  is  usually  flattened  and  black  so  that  when  cleaning  out  the  boxes 
miners  are  often  seen  biting  a nugget  to  make  sure  that  it  is  gold  and  not 
one  of  the  iron  stones.  Quartz  is  at  times  embedded  in  the  larger  nuggets  and 
gold  is  observed  now  and  then  in  the  form  of  fine  veinlets  through  the  iron 
stones.  One  nugget  weighing  $62.10  and  a second  weighing  $36  have  been 
taken  from  the  creek. 

Black  sand  is  unknown  in  the  clean  ups ; pyrite  and  a few  small  pieces  of 
rutile  which  occasionally  have  been  mistaken  by  the  miners  for  tin  ore  are 
the  heavy  minerals  associated  with  the  gold;  it  is  not  considered  a favorable 
sign  when  the  iron  stones  fail. 

So  far  as  is  known  all  of  the  material  in  the  Candle  Creek  placers 
is  of  local  origin,  although  the  source  of  the  gold  in  bed  rock  has 
not  been  determined. 

° Moffit,  F.  H.,  The  Fairhaven  gold  placers,  Seward  Peninsula,  Alaska : Bull.  U.  S. 
Geol.  Survey  No.  247,  1905. 

Henshaw,  F.  F.,  Mining  in  the  Fairhaven  precinct : Bull  U.  S.  Geol.  Survey  No.  379, 
1909,  pp.  364-369. 

b Moffit,  F.  H.,  op.  cit.,  p.  62. 


127 


NORTON  BAY-NULATO  REGION,  ALASKA. 

During  the  early  development  of  this  region  considerable  difficulty 
was  experienced  owing  to  the  lack  of  a sufficient  supply  of  water 
for  mining.  This  deficiency  was  met  in  part  by  the  construction  of 
short  ditches  within  the  Candle  Creek  basin,  but  as  the  supply  was 
still  inadequate  a ditch  over  33  miles  in  length  was  built  in  1907 
along  the  west  band  of  Kiwalik  River  from  the  mouth  of  Glacier 
Creek  to  the  mouth  of  Candle  Creek.  This  ditch  has  a capacity  of 
20  to  30  second-feet  and  the  height  of  the  lower  end  above  Kiwalik 
River  at  that  point  is  about  250  feet.  Henshaw  ° in  the  report  already 
mentioned  suggests  that  the  most  practical  method  of  obtaining  a 
larger  water  supply  is  by  pumping  from  Kiwalik  River.  Power  for 
such  an  enterprise  might  be  derived  either  by  using  Chicago  Creek 
coal  as  fuel  or  by  the  transformation  of  water  power  below  Imuruk 
Lake  into  electricity. 

SUMMARY. 

From  the  distribution  of  the  areas  where  placers  of  ' economic  im- 
portance have  been  mined  certain  facts  of  value  in  assisting  further 
prospecting  may  be  learned.  Some  of  the  more  evident  conclusions 
are  as  follows : The  Cretaceous  areas  are  not  promising  placer  regions 
and  neither  are  those  places  promising  that  derive  their  deposits 
mainly  from  Cretaceous  rocks,  as,  for  instance,  the  marine  deposits 
on  the  east  shore,  of  Norton  Ba}^ ; no  placers  of  other  than  distinctly 
local  importance  occur  in  regions  deriving  their  gravels  from  the  pre- 
Cretaceous  igneous  rocks;  no  placers  at  all  have  been  found  in  the 
gravels  derived  solely  from  the  recent  effusive  rocks;  no  gravel 
deposits  derived  entirely  from  the  limestones  of  Paleozoic  age  contain 
gold  in  workable  quantities;  local  placers  may  occur  near  the  post- 
Cretaceous  intrusions;  the  most  extensive  placers  occur  in  the  areas 
of  metamorphic  sedimentary  schists,  especially  near  their  contact 
w7ith  the  heavy  limestones ; gold  placers  are  usually  found  where  con- 
centration of  gravel  derived  from  the  Paleozoic  black  quartzite  has 
occurred.  These  general  conditions  are  modified  by  local  conditions ; 
thus  in  places  where  concentration  has  been  strong  richer  deposits  are 
to  be  expected  than  in  places  where  less  sorting  has  occurred.  From 
this  fact  it  follows  that  the  glaciated  areas  hold  less  promise  of  placer 
deposits  than  the  unglaciated  areas. 

LODE  PROSPECTS. 

Although,  as  has  been  shown,  placer  gold  has  been  found  on  many 
of  the  streams  in  the  area  of  metamorphic  rocks,  no  veins  sufficiently 
rich  to  allow  lode  mining  have  been  discovered.  This  is  probably 
in  part  due  to  the  absence  of  adequate  prospecting.  Quartz  veins 


Henshaw,  F.  F.,  op.  cit.,  p.  368. 


128  RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 

containing  gold  have  been  found  at  many  places  and  at  a few  places 
pits  have  been  sunk;  copper  sulphides  have  also  been  found;  and 
silver-bearing  galena  has  been  known  almost  since  the  first  white 
men  visited  the  region. 


GOLD  LODE  PROSPECTS. 

In  order  to  give  an  idea  of  the  places  where  auriferous  veins  have 
been  exploited  the  following  notes  may  be  of  service. 

A sample  taken  from  the  schists  adjacent  to  some  quartz  stringers 
near  the  mouth  of  Ophir  Creek  contained  gold  in  such  quantities 
that  when  crushed  in  a hand  mortar  and  panned  free  gold  was 
obtained.  On  Crooked  Creek,  a tributary  of  Ophir  Creek,  there  “ is 
a mineralized  belt  12  feet  wide  which  strikes  northwest.  In  this 
impregnated  zone  vein  quartz  is  associated  with  pyrite.  It  is  re- 
ported to  assay  as  high  as  $8  to  the  ton.”  ° Near  this  place,  on  the 
divide  between  Goldbottom  and  Crooked  creeks,  is  a gold-bearing 
vein  which  seems  to  be  a continuation  of  this  lead.  Mineralization  on 
a small  scale  has  been  recognized  at  several  places  on  Goldbottom 
and  Warm  creeks,  and  a short  distance  from  the  mouth  of  Warm 
Creek  a vein,  on  which  some  development  work  had  been  done,  was 
found  at  the  contact  of  schist  and  limestone.  “ Near  the  mouth  of 
the  creek  [Warm  Creek]  are  two  quartz  veins,  one  about  3 feet  wide 
and  the  other  about  1 foot  wide,  striking  N.  30°  E.”  h 

No  productive  lodes  have  so  far  been  found  in  the  Bluff  region. 
Brooks  says : c 

So  far  as  observed,  the  schists  appear  to  be  mineralized  only  near  their  con- 
tacts with  the  limestones.  At  these  places  quartz  veins  cutting  the  foliation 
of  the  schists  are  not  uncommon.  The  individual  veins  appear  to  be  of  small 
extent,  but  at  some  localities  a stockwork  forms  a considerable  mass  of  low- 
grade  ore.  The  ores  appear  to  be  chiefly  iron  pyrite  with  some  chalcopyrite 
and  arsenopyrite.  * * * 

An  impregnated  zone  is  well  exposed  along  the  sea  cliff  about  three-fourths 
of  a mile  east  of  the  mouth  of  Daniels  Creek.  * * * At  this  locality  a belt 

of  mica  schist  about  60  feet  wide  is  more  or  less  impregnated  by  pyrite-bearing 
quartz  stringers.  The  belt,  including  some  irregular  limestone  masses,  is 
bounded  by  graphitic  limestone  walls  which  dip  away  from  the  schists  and  form 
a small  anticline  much  broken  by  faults.  * * * At  the  west  contact  a band 

of  schist  20  feet  in  cross  section  lies  between  one  of  the  included  limestone 
masses  and  the  country  rock.  In  this  band  the  mineralization  is  more  intense 
than  in  the  rest  of  the  schist.  Here  a series  of  gash  veins,  the  largest  of  which 
is  18  inches  in  width,  cut  the  foliation  of  the  schist.  [See  fig.  15.]  A mass  of 
crushed  material  or  gouge  forms  the  hanging  wall  of  this  deposit  and  along 
this  zone,  which  has  been  a plane  of  movement,  the  quartz  veins  are  cut  off 
abruptly.  Stringers  of  quartz  do,  however,  occur  in  the  limestone  on  both 
sides  of  the  schist.  The  ore  appears  to  be  chiefly  iron  pyrite  and  mispickel, 
with  some  chalcopyrite ; the  gangue  is  mostly  quartz,  with  some  calcite. 


° Collier,  A.  J.,  and  others,  op.  cit.,  p.  252. 
6 Idem,  p.  255. 

c Brooks,  A.  II.,  op.  cit.,  pp.  285-292. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


129 


Although  this  mineralized  zone  was  known  for  several  years  not 
much  active  exploitation  was  undertaken  until  1907.  At  one  claim  a 
shaft  50  feet  deep  was  sunk  and  a short  drift  about  15  feet  in  length 
was  turned  off.  On  the  adjoining  claim  the  zone  of  mineralization 
is  so  wide  that  two  shafts,  one  on  the  hanging  wall  and  one  on  the 
foot  wall,  have  been  sunk.  One  of  these  is  reported  to  be  100  feet 
deep;  the  other  is  slightly  less  than  half  that  depth.  On  the  next 
claim,  also,  two  shafts  have  been  sunk  to  a depth  of  approximately 
50  feet.  Two  shorter  shafts  have  been  put  down  on  the  next  claim, 
and  one  shaft  about  75  feet  deep  has  been  sunk  near  the  end  line  of 
the  next  claim  beyond.  In  1907  the  ore  from  these  properties  was 
crushed  in  an  arrastra  which  was  operated  by  a horse;  it  was  in- 
tended to  erect  a stamp  mill  later. 

The  developments  at  this  place,  how- 
ever, have  not  been  ascertained  for 
the  last  two  years. 

According  to  Brooks,  in  1906  a 
lode  3 miles  east  of  Bluff  had  been 
developed  to  some  extent.®  It  was 
located  near  the  shore,  and  was  said 
to  be  14  feet  wide  and  to  yield  as 
much  as  $30  in  gold  to  the  ton.  The 
ore  is  reported  to  be  iron  pyrite  and 
mispickel.  A few  tons  have  been 
sacked  and  prepared  for  shipment  but  practically  nothing  is  known 
about  the  mode  of  occurrence. 

A small  amount  of  prospecting  has  been  done  near  the  head  of 
Walla  Walla  Creek  somewhat  east  of  the  contact  of  the  igneous  rocks 
and  the  black  quart zitic  slates.  Although  rich  specimens  are  said  to 
have  been  found  here,  a careful  examination  of  the  rock  on  the  dump 
failed  to  disclose  enough  mineralization  to  encourage  further  pros- 
pecting. A small  amount  of  limonite  staining  the  joints  and  fracture 
planes  of  the  rocks  was  observed,  but  there  is  no  vein  or  distinct  lead. 
Developments  at  this  place  consist  of  an  open  cut  about  25  feet  long 
and  a crosscut  adit,  started  about  500  feet  away  and  down  the  hillside, 
which  has  gone  in  38  paces  (about  100  feet),  all  the  way  through  bar- 
ren rock.  An  analysis  of  rock  from  this  open  cut  by  Peter  Esch,  of 
Nome,  gave  a trace  of  gold. 

As  placer  gold  is  derived  from  veins,  it  is  certain  that  auriferous 
veins  must  occur  widely  throughout  the  area.  Whether  such  veins 
can  be  economically  mined  is  a question  which  can  be  decided  only  by 
more  active  development.  It  is  probable  that  if  auriferous  veins  are 

° Brooks,  A.  H.,  op.  cit.,  p.  292. 

71469°— Bull.  449—11 9 


Figure  15. — Diagrammatic  section  of 
impregnated  zones,  Bluff  region. 


130 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


exploited  in  the  future  the  mining  problems  involved  will  fall  within 
commercial  rather  than  geologic  boundaries. 

SILVER-LEAD  DEPOSIT. 

Within  the  area  of  metamorphic  rocks  of  southeastern  Seward 
Peninsula  one  deposit  of  argentiferous  galena  has  been  of  some  eco- 
nomic value.  This  lode,  staked  in  1881,  was  probably  the  second 
one  discovered  in  the  entire  territory  of  Alaska.  Although  the  claims 
were  not  recorded  until  July,  1881,  galena  had  been  known  for  a year 
or  more  before,  and  Petrof,  in  the  census  report  for  1880,  mentions 
that  silver-lead  ore  had  been  found  in  the  vicinity  of  Golofnin  Bay. 
The  developments  at  this  place  have  been  carried  on  at  a single  group 
of  claims  located  on  a l6w  limestone-schist  hill  on  the  western  flanks 
of  the  Darby  Range.  As  has  already  been  stated,  the  claims  were 
located  in  1881.  In  1882  a company  was  formed  which  in  1883  was 
absorbed  by  the  Omilak  Gold  and  Silver  Mining  Company,  which 
continued  to  hold,  the  ground  until  1898,  when  the  Russian- American 
Mining  Exploration  Companj^  took  the  properties.  This  transfer 
was  one  of  name  rather  than  of  personnel.  The  claims  were  patented 
in  1894. 

The  geology  in  the  vicinity  of  the  mine  is  so  complex  that  without 
more  detailed  study  than  was  made  in  1909  the  stratigraphy  is  not 
determinable.  East  of  the  mine,  toward  the  head  of  Omilak  Creek, 
is  a large  area  of  white  crystalline  limestone,  which,  in  the  main, 
appears  to  dip  westward  at  high  angles.  This  is  succeeded  farther 
west  by  schistose  rocks  containing  much  biotite  and  quartz  and  some 
graphite.  Still  farther  west,  in  the  immediate  neighborhood  of  the 
mine,  the  distribution  of  the  various  rocks  is  as  shown  in  figure  6 
(p.  64) . Although  from  this  map  it  appears  that  the  dip  is  in  general 
to  the  west,  the  evidence  on  the  ground  shows  that  the  rocks  are  much 
deformed,  and  appressed  folds,  such  as  are  shown  in  Plate  XIII,  A 
(p.  90),  have  been  recognized.  This  fold,  which  pitches  steeply 
toward  the  west,  is  shown  at  A on  figure  6 (p.  90).  It  is  evident  that 
with  such  an  amount  of  folding  this  structure  is  by  no  means  so  simple 
as  appears  at  first  sight,  and  even  the  determination  of  bedding  is 
often  impossible.  It  is  believed,  though  it  has  not  been  definitely 
proved,  that  the  schists  represent  younger  or  overlying  rocks. 

In  addition  to  the  dark  biotite  schist  and  the  limestones  there  is 
an  area  of  slightly  sheared  igneous  rock  similar  to  the  greenstones 
of  the  more  western  part  of  Seward  Peninsula.  Although  the  ex- 
posures were  not  sufficiently  clear  to  preclude  other  interpretations, 
it  seems  probable  that  these  greenstones  intrude  the  limestones. 
Owing  to  the  amount  of  deformation  and  consequent  metamorphism 
it  is  probable  that  some  of  the  greenstones  are  included  in  the  areas 


NORTON  BAY-NULATO  REGION,  ALASKA. 


131 


mapped  as  schist.  The  fact  that  the  greenstone  is  more  easily  recog- 
nizable in  the  midst  of  the  limestone  may  be  due  to  the  protection 
given  it  by  that  rock,  which  is  more  easily  deformed  than  the  schist, 
whose  resistance  to  dynamic  metamorphism  is  more  nearly  equal  to 
that  of  the  igneous  rocks. 

According  to  Mendenhall  the  ore  occurs  near  the  contact  of  this 
intrusive  and  the  limestone.®  From  the  study  of  the  region  in  1909 
this  conclusion  could  not  be  verified  as  the  shaft  was  inaccessible  and 
the  only  mineralization  seen  was  in  the  midst  of  the  limestone.  In 
the  absence,  however,  of  ore-bearing  minerals  in  the  greenstone  it 
seems  doubtful  whether  the  galena  could  have  been  introduced  at 
the  time  of  the  intrusion.  Furthermore,  the  well  crystallized  charac- 
ter of  the  ore  suggests  that  its  deposition  was  later  than  the  deforma- 
tion of  the  region,  whereas  the  greenstone  was  earlier. 

Two  kinds  of  ore  minerals  are  found  in  this  deposit — argentiferous 
galena  and  stibnite.  So  far  no  interrelation  between  the  two  has 
been  shown,  but  it  is  believed  that  both  were  introduced  at  essentially 
the  same  time.  It  should  be  noted  that  the  deposits  containing  the 
galena  seem  to  be  topographically  above  those  with  stibnite. 

From  the  reports  of  others — as  it  was  not  possible  to  see  the  under- 
ground workings  personally — it  was  learned  that  “ no  continuous 
vein  of  galena  ore  existed,  the  ore  being  found  only  in  irregular 
and  disconnected  pockets.”* 6  None  of  the  pockets  were  of  large  size 
and  the  better  ones  occurred  entirely  within  the  limestone.  Some  of 
the  ore  was  thickly  covered  with  products  of  oxidation,  mostly  lead 
carbonate. 

About  400  paces:  south  of  the  galena  shaft  there  are  a shaft  and  an 
incline  which  were  used  to  explore  the  stibnite  leads.  The  limestone 
is  much  fractured  and  the  ore  occurs  in  thin  streaks  in  the  shattered 
zone.  None  of  the  veins  seen  by  the  writers  are  of  sufficient  size  to 
warrant  mining.  The  stibnite  is  well  crystallized,  the  thicker 
stringers  apparently  occupying  fault  planes  and  sending  small  off- 
shoots into  the  limestone,  which,  near  the  ore,  is  abnormally  granular 
and  sugary. 

Considering  the  number  of  years  the  ground  has  been  held  and  the 
large  expenditures  incurred,  the  amount  of  development  work  is 
astonishingly  small.  A shaft  180  feet  deep  has  been  sunk  near  the 
eastern  margin  of  the  limestone  on  top  of  the  hill,  and  two  short 
drifts  have  been  turned  off  in  the  search  for  ore  pockets.  The  upper 
part  of  the  shaft  is  in  limestone,  but  the  lower  is  in  schist,  as  the  con- 
tact dips  toward  the  west.  The  shaft  is  well  timbered  and  is  fairly 
dry.  Hoisting  is  done  by  power,  a bucket  not  running  on  guides 

“ Mendenhall,  W.  C.,  op.  cit.,  p.  214. 

6 Idem,  pp.  213-214. 


132 


RECONNAISSANCE  IN  SEWARD.  PENINSULA  AND 


being  used.  Electric  lights  are  used  around  the  shaft  hpuse  and 
underground.  Two  outfits  for  drilling  have  been  used,  one  an  air 
compressor  and  air  drills  and  the  other  an  electric  drill  plant.  Elec- 
tricity for  these  uses  is  furnished  by  a coal- oil  engine  located  near 
the  main  bunk  house  on  Omilak  Creek. 

At  200  to  300  feet,  vertically,  above  Omilak  Creek  an  adit  has  been 
started  to  intersect  the  shaft  in  depth  and  thus  obviate  the  necessity 
of  hoisting  the  rock  to  the  top  of  the  hill  and  then  taking  it  down 
again  for  shipment.  The  length  of  the  adit  is  1ST  paces,  or,  approxi- 
mately, 500  feet;  this  distance  was  in  massive  white  limestone  some- 
what shattered,  but  nowhere  showing  mineralization. 

In  addition  to  the  equipment  directly  at  the  mine  there  are  bunk 
and  store  houses  at  Cheenik,  on  Fish  River,  and  also  half  a mile  or  so 
below  the  mine  on  Omilak  Creek.  At  the  latter  place  are  a repair 
shop,  electric  plant,  assay  laboratory,  electric  sawmill,  stable,  and 
the  other  equipment  usually  found  only  at  large  producing  mines. 
The  company  also  owns  a large  river  steamer  originally  built  for 
freighting  the  mine  supplies  up  the  river,  but  it  has  never  been  used. 

The  production  of  the  mine  is  not  definitely  known,  but  it  has  prob- 
ably not  been  more  than  400  nor  less  than  300  tons.  A part  of 
this  was  obtained  from  the  various  pockets  below  ground,  but  a con- 
siderable amount  is  understood  to  have  come  from  hand  picking  the 
float  found  on  the  hillside.  The  following  tables  show  the  returns 
from  assays  of  the  ore  as  shipped.  It  should  be  noted  that  owing  to 
the  high  transportation  charges  the  ore  was  carefully  hand  picked 
and  in  some  cases  washed  before  shipping. 


Returns  from  assays  of  ore  as  shipped  from  Omilak  mine. 


Weight 

(pounds). 

Gold 
(value 
per  ton). 

Silver 
(value 
per  ton). 

Lead 
(pounds 
per  ton). 

Lead 
(value 
per  ton). 

Total 
value 
per  ton. 

1 

4,230 

137.29 

1,538 

61.52 

198.81 

2 

545 

2.07 

106. 62 

1,320 

52.80 

161. 49 

3 

130,000 

3.09 

98.72 

1,128 

45. 12 

146.93 

4 

68,078 

104. 00 

1,300 

52.00 

156.00 

5 

12, 167 

2.07 

125. 19 

1,440 

57.60 

184.86 

6 

82, 100 

132. 95 

1,494 

59.76 

192. 71 

7 

86,885 

7.43 

49.60 

502 

20.08 

77.11 

8 

27,787 

1.54 

41.40 

606 

24.24 

67. 18 

9 

13, 606 

1.54 

38. 10 

566 

22.64 

62.28 

10 

2, 675 

1.03 

54.93 

770 

30.80 

86.76 

11 

6,569 

2.07 

46.46 

890 

35.60 

84. 13 

12 

164 

7.53 

65.54 

816 

32. 64 

105.71 

13 

595 

2.07 

71.15 

980 

39.20 

112. 42 

14 

380 

2.07 

86.86 

966 

38.  64 

127. 57 

15 

26, 175 

2. 07 

120. 33 

1,222 

48.88 

171.  28 

1 to  6 inclusive,  solid  ore  from  Omilak  mine,  tons  of  2,000  lbs. ; 7 to  14,  inclusive,  car- 
bonate ores  from  Omilak  mine ; 15,  carbonate  ore  concentrated  by  washing  in  sluice  boxes. 


Unfortunately,  in  these  assays  the  data  are  not  sufficient  to  deter- 
mine the  percentage  of  any  of  the  constituents  except  the  lead,  and 


NORTON  BAY-NULATO  REGION,  ALASKA.  133 

therefore  the  following  assays,  less  complete  in  certain  other  ways, 
are  given  also : 

Silver  and  lead  in  ore  from  Omilak  mime. 


Silver 
(ounces 
per  ton). 

Lead 

(per 

cent). 

1 

173. 00 

75.0 

2 

141.00 

80.7 

3 

158. 00 

78.0 

4 

153. 70 

82.0 

5 

162. 97 

78.5 

6 

149.16 

73.0 

7 

142  20 

74.7 

8 

94. 30 

55.9 

9 

60.7 

10.  27 

Assays  1-2  by  Herford  Copper  Works,  Swansea,  England ; 3 by  Pennsylvania  Lead 
Company,  Pittsburg,  Pa. ; 4-6  by  W.  P.  Miller,  San  Francisco  ; 7 by  T.  Price,  San  Fran- 
cisco ; 8-9  reported  by  W.  C.  Mendenhall,  op.  cit.,  p.  214  ; 8 yellow  carbonate  ore ; 9 
red  carbonate  ore. 

Assays  and  relative  weights  of  part  of  the  different  ores  shipped 
by  the  Omilak  mine  in  1889,  with  the  price  paid  in  open  market  for 
the  same  are  given  in  the  following  table : 


Assays  and  weights  of  ore  shipped  by  Omilak  mine  in  1889. 


Commercial  name. 

Weight 

(pounds). 

Gold 
(ounces 
per  ton). 

Silver 
(ounces 
per  ton). 

Lead 

(per 

cent). 

Price 
received 
per  ton. 

Red  carbonate 

380 

0.1 

92.9 

48.3 

$93.00 

Grav  carbonate 

595 

.1 

76.1 

49.0 

81.00 

Yellow  carbonate 

6,569 

.1 

49.7 

44.5 

57. 00 

Argentiferous  galena 

82, 100 

142.2 

74.7 

154.00 

It  is  evident  that  the  ore  is  high  in  silver  and  also  usually  carries 
a small  quantity  of  gold.  Its  metallurgical  treatment  is  simple  and 
the  ore  is  especially  valuable  to  mix  with  other  more  refractory  ores. 
The  absence  of  fuel  at  a reasonable  price  prevents  treatment  near  the 
mine  and  the  high  charges  for  transportation  restrict  shipments  to 
ores  of  the  higher  grade. 

From  the  foregoing  descriptions  certain  facts  are  evident,  which 
may  be  summarized  as  follows:  The  claims  have  been  inadequately 
prospected  and  large  expenditures!  have  been  made,  apparently  with- 
out disclosing  a workable  vein ; the  ore  found  is  of  excellent  quality, 
but  the  quantity,  so  far  as  could  be  determined  by  the  writers,  is  not 
sufficient  to  warrant  extensive  developments.  The  most  promising 
area  to  prospect  is  in  the  limestone  near  its  contact  with  the  schists, 
but  the  deposits  likely  to  be  found  will  probably  be  pockets  not 
easily  adaptable  to  cheap  mining  methods  and  not  capable  of  afford- 
ing a large,  constant  amount  of  ore. 


134 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


COPPER  PROSPECTS. 

Attempts  have  been  made  to  develop  copper  leads  at  three  places 
within  the  Nulato-Council  region,  but  so  far  the  results  have  not  been 
encouraging,  and  the  general  absence  of  sulphide  mineralization 
throughout  Seward  Peninsula  leads  one  to  doubt  whether  commer- 
cially important  deposits  of  copper  will  be  found.  Furthermore,  the 
necessary  treatment  and  refining  that  copper  must  undergo  before 
manufacture  makes  this  metal  difficult  to  handle  in  a country  where 
high  wages,  high  cost  of  supplies,  and  absence  of  transportation  facil- 
ities exist.  It  seems  likely,  therefore,  that  until  one  or  all  of  these 
factors  are  canceled  or  reduced,  copper  mining  can  be  successfully 
carried  on  only  where  the  deposit  is  exceptionally  rich.  No  such 
places  are  at  present  known  in  Seward  Peninsula. 

Several  shallow  prospect  pits  were  sunk  in  1906-7  in  the  hills  near 
Timber  Creek  in  the  Tubutulik  divide,  on  copper-stained  greenstones, 
near  their  contact  with  limestone.  A large  outfit  was  shipped  in  and 
extensive  plans  formulated,  but  the  mineralization  was  not  sufficient 
to  warrant  development,  and  after  a little  desultory  prospecting  the 
ground  was  abandoned.  Specimens  of  the  ore  from  this  claim  were 
assa}red  and,  according  to  the  owners,  yielded  from  17  to  70  ounces 
of  silver  to  the  ton  and  from  a few  cents  to  $1  a ton  in  gold  as  well 
as  copper.  From  the  high  copper  content  reported  in  these  assays, 
it  is  evident  that  the  sample  for  assay  was  carefully  hand-picked. 
From  a personal  examination  of  specimens  from  this  ground  it 
appeared  to  the  writers  that  the  copper  occurred  almost  exclusively 
in  the  form  of  malachite,  the  green  carbonate  of  copper,  and  sul- 
phides or  other  original  minerals  were  practically  absent.  On  account 
of  the  secondary  character  of  the  ore,  it  is  difficult  to  ascertain  the 
time  or  mode  of  origin  of  the  copper  mineralization.  The  observed 
facts  show  that  the  carbonate  occupies  fractures  and  joints  in  the 
greenstone,  but  this  does  not  preclude  its  having  been  derived  from 
the  leaching  of  copper  minerals  originally  present  in  the  greenstone. 
So  far  as  could  be  determined,  the  copper  mineralization  at  this  place 
is  distinctly  local  and  in  such  insignificant  quantity  as  to  discourage 
further  investigation. 

On  the  east  coast  of  the  Darby  Peninsula,  about  3 miles  north  of 
Carson  Creek,  a little  copper  mineralization  was  observed.  A small 
amount  of  exploration  by  means  of  a short,  open  cut  had  been  made, 
but  no  work  was  in  progress  at  the  time  of  the  visit  in  1909.  The 
copper  occurs  mainly  in  the  form  of  the  carbonate,  but  there  is  also 
a little  chalcocite  present.  This  ore  does  not  occur  in  a vein,  but 
seems  to  be  a replacement  of  parts  of  the  schist,  so  that  its  distribution 
is  irregular  and  discontinuous.  Some  is  also  found  in  the  joint  planes, 
as  though  it  had  been  introduced  later  than  the  deformation  of  the 
country  rock.  There  is  a large  amount  of  slickensiding  on  the  rocks, 


NORTON  BAY-NTJLATO  REGION,  ALASKA. 


135 


showing  that  faulting  has  occurred,  and  it  is  by  no  means  improbable 
that  the  shattering  effected  by  these  movements  may  have  produced 
a more  or  less  pervious  zone,  which  allowed  easy  penetration  for 
mineralizing  solutions.  The  amount  of  mineralization  is,  however, 
slight,  and  there  seems  to  be  no  reason  for  believing  that  a commer- 
cially workable  deposit  will  be  found  at  this  place. 

A short  distance  farther  south  is  an  outcrop  of  a nearly  pure  white 
limestone,  which,  though  slightly  sheared,  is  in  places  much  brec- 
ciated.  A short  tunnel  has  been  driven  in  on  this  brecciated  band. 
Apparently  some  surface  stains  had  tempted  exploitation,  but  as  the 
work  progressed  and  no  vein  or  other  mineralization  was  found  the 
search  was  abandoned.  From  the  present  condition  of  the  tunnel  and 
the  surrounding  country  rock  one  fails  to  understand  why  mining  was 
ever  contemplated  at  this  place. 

The  only  other  place  where  copper  prospecting  has  been  under- 
taken within  the  Nulato- Council  region  is  in  the  Bendeleben  Moun- 
tains on  the  divide  between  Kingsland  and  Nugget  creeks.  These 
streams  are  tributaries  of  the  Niukluk  from  the  east  about  4 miles 
south  of  the  Birch  Creek-Niukluk  divide.  Prospecting  in  this  region 
has  been  carried  on  for  five  to  eight  years,  but  no  shipment  of  ore 
has  been  made  and  no  considerable  body  has  been  exposed.  The 
ore  occurs  near  the  contact  of  a limestone  and  schist  in  a region  much 
faulted  and  intruded  by  small  granite  dikes.  The  ore  is  low  grade 
and  consists  mainly  of  chalcopyrite,  with  few  alteration  products. 
No  distinct  vein  Tvas  found,  the  ore  occurring  mainly  as  a replace- 
ment of  the  country  rock  in  disseminated  lenses  and  strings.  A little 
gold  is  reported  to  be  associated  with  the  copper,  but  neither  its 
value  nor  its  relation  to  the  copper  mineralization  was  learned. 

Although  of  no  commercial  value,  the  occurrence  of  copper 
sulphides  in  a pink  granite,  with  rather  large  feldspar  crystals,  on 
the  upper  part  of  Peace  River  2 or  3 miles  above  camp  B13,  is  noted 
as  giving  a suggestion  of  the  time  of  introduction  of  some  of  the 
copper  mineralization.  At  this  place  there  is  only  a little  copper, 
but  it  seems  to  have  been  brought  in  contemporaneously  with  the 
granite.  As  there  is  no  evidence  at  the  other  places  already  de- 
scribed of  the  age  of  the  mineralization,  this  occurrence  becomes 
significant. 

From  the  preceding  accounts  of  the  meager  amount  of  development 
work  on  copper  lodes  it  is  evident  that  no  deposits  of  value  are 
known.  In  part  this  may  be  due  to  lack  of  thorough  investigation, 
but  it  is  believed  to  be  due  in  the  main  to  the  absence  of  cupriferous 
veins.  Therefore,  although  valuable  copper  may  be  discovered  in 
the  future,  the  present  conditions  do  not  warrant  search  unless  the 


136 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


enterprise  is  undertaken  with  the  knowledge  that  the  chances  are 
against  rather  than  in  favor  of  success. 

COAL  RESOURCES. 

Wherever  the  Cretaceous  sediments  are  extensively  developed 
throughout  Alaska  there  are  indications  of  coal.  Some  of  these  crop- 
pings in  the  area  under  discussion  have  been  prospected  and  claims 
staked.  Field  examinations  of  some  of  the  Alaskan  coal  deposits 
along  Yukon  River  have  been  recently  completed  by  Atwood,  but 
the  results  have  not  yet  been  made  available.  Manuscript  notes  of 
the  facts  gathered  b}^  him  concerning  the  Nulato  region  have,  how- 
ever, been  furnished  and  have  been  of  service  in  preparing  the 
following  paragraphs. 

Fossils  have  not  been  found  at  many  of  the  coal  prospects  and  it  is 
impossible  to  refer  the  various  beds  definitely  to  their  proper  geologic 
horizons.  Closer  correlations  therefore  than  that  the  coals  belong 
to  the  Upper  Cretaceous  will  not  be  attempted,  although  it  is  believed 
that  most  of  the  deposits  belong  to  the  lower  rather  than  the  higher 
part  of  this  series.  One  exception,  in  which  the  material  is  a very 
woody  lignite,  seems  to  be  of  much  more  recent  age  and  is  provision- 
ally called  post-Tertiary,  mainly  on  account  of  its  physical  character. 

For  convenience  of  description  a geographic  order  will  be  adopted. 
According  to  this  plan,  the  deposits  have  been  divided  into,  fi’rst, 
those  occurring  in  the  Yukon  River  drainage  basin,  and,  second,  those 
either  in  regions  draining  into  Norton  Bay  or  in  Seward  Peninsula. 

YUKON  BASIN. 

The  most  eastern  locality  where  coal  has  been  prospected  in  this 
part  of  the  Yukon  basin  is  at  Nahoclatilten  or  Louden,  west  of  the 
mouth  of  the  Melozitna.  A description  of  these  coals  by  Collier  is 
as  follows : a 

Two  beds  of  coal  were  seen  by  the  writer  at  this  place,  and  two  more  are 
reported  to  have  been  uncovered  in  prospecting.  The  largest  observed  seam  has 
a thickness  of  1 foot.  Below  this  seam  there  are  about  5 feet  of  bony  coal  or 
coaly  shale  with  stringers  of  coal.  There  are  reported  to  be  3 smaller  beds  in 
the  foot  wall,  each  having  a thickness  of  10  inches.  Owing  to  the  apparent 
rather  intense  folding  of  these  beds,  it  is  impossible  to  place  much  reliance  on 
these  statements. 

The  coal  in  the  1-foot  seam  is  not  crushed,  although  the  beds  are  much  dis- 
turbed in  position.  The  following  analysis  shows  it  to  be  a bituminous  coal  of 
good  quality.  It  is  reported  to  have  given  satisfactory  results  in  a blacksmith’s 
forge. 


° Collier,  A.  J.,  The  coal  resources  of  the  Yukon,  Alaska  : Bull.  U.  S.  Geol.  Survey  No. 
218,  1903,  pp.  47-48. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


137 


Analysis  of  coal  (No.  2^1)  from  1-foot  seam  5 miles  above  Nahoclatilten. 


[Analyst,  E.  T.  Allen,  U.  S.  Geol.  Survey.] 


Water 

Volatile  combustible  matter. 

Fixed  carbon 

Ash 


Ter  cent. 
. 6.88 
. 41. 82 

48.  93 
2.37 


100.  00 

Sulphur .65 

Fuel  ratio 1. 17 


Coke  slightly  coherent. 

These  coal  beds  have  been  known  for  several  years,  and  various  attempts 
have  been  made  to  open  here  coal  beds  of  commercial  importance,  but  thus  far 
no  seams  thicker  than  12  inches  have  been  found. 

No  other  coal  prospects  have  been  noted  lower  down  on  the  Yukon 
until  about  midway  between  the  mouth  of  the  Koyukuk  and  Nulato. 
A mine,  called  from  its  owner  the  Pickart  mine,  was  noted  by 
Schrader  in  1899 ; it  is  therefore  one  of  the  oldest  coal  mines  in 
Alaska.  According  to  Collier : a 

At  the  Pickart  mine  one  coal  seam  has  been  exploited  which  strikes  N.  75°  E. 
and  dips  35°  N.  Two  rolls,  or  horsebacks,  are  reported  to  occur  in  the  floor 
of  the  coal  bed.  Whether  these  are  in  the  nature  of  faults  due  to  movemerit 
of  strata  along  the  coal  bed  or  irregularities  in  deposition  of  the  sediments 
constituting  the  floor  the  writer  was  unable  to  determine.  Near  these  rolls 
the  coal  shows  considerable  crushing,  which  suggests  that  the  roll  is  formed 
by  deformation.  The  Pickart  coal  bed  has  a thickness  of  30  inches  at  a dis- 
tance of  300  feet  from  the  entrance  to  the  mine,  but  near  one  of  the  rolls  above 
referred  to  the  seam  measured  only  18  inches.  Mr.  W.  E.  Williams,  manager 
of  the  Pickart  mine,  reports  that  in  mining  this  coal  a roll  was  encountered 
in  the  workings  above  the  coal  mine  gangway  in  which  the  floor  of  the  bed 
was  raised  up,  pinching  the  coal  down  to  a knife-edge  thickness.  The  roll  ex- 
tended in  a nearly  straight  line  and  approached  the  gangway  at  a rate  of 
about  1 foot  in  20.  On  cutting  through  this  roll  good  coal  was  found. 

Analyses  of  the  coal  from  near  this  mine  published  by  Collier  are 
as  follows:6 


Analyses  of  semibituminous  coking  coal  on  the  Yukon. 

[No.  1 from  12  miles  above  Nulato,  on  the  Yukon  ; analyst,  George  Steiger,  U.  S.  Geol. 
Survey.  Nos.  2 and  3 from  Pickart  mine,  on  the  Yukon  ; analyst,  E.  T.  Allen,  U.  S. 
Geol.  Survey.] 


1. 

2. 

3. 

Moisture 

0. 86 

1.02 

1.64 

Volatile  matter 

25. 75 

27. 33 

24.98 
58. 18 

Fixed  carbon 

66. 51 

65.03 

Ash ' 

6.88 

6.62 

15. 20 

Sulphur 

.56 

Fuel  ratio 

2. 22 

2. 37 

2.32 

• Collier,  A.  J.,  op.  cit.,  p.  50.  6 Idem,  p.  62. 


138 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


In  1907  this  mine  was  visited  by  Atwood,  who  reports  that  no 
work  had  been  in  progress  for  several  years.  According  to  him 
there  are  at  least  four  thin  seams  of  coal  stratigraphically  higher 
than  the  one  the  mine  was  opened  on.  These  upper  beds  are  only 
from  6 to  8 inches  in  thickness,  and  are  associated  with  carbonaceous 
shales,  which  show  frequent  signs  of  cross-bedding  and  ripple  marks. 

About  a mile  above  Nulato,  Collier  noted  a prospect  hole  sunk 
in  the  sandstones  called  Nulato  sandstone  by  Dali.  The  section  ex- 
posed showed  2J  feet  of  bony  coal  with  several  bands  of  clay.  One 
6-inch  bed  of  clean  coal  was  uncovered  and,  it  is  reported,  was  used 
to  some  extent  for  blacksmithing  at  Nulato.  There  has  been  no 
recent  work  at  this  prospect,  and  it  is  evident  that  the  seam  is  too 
thin  to  invite  further  investigation. 

Four  miles  below  Nulato,  in  the  name  sandstone  in  which  the  other 
prospects  already  described  occur,  is  a coal  bed  that  has  been  opened 
to  a small  extent.  This  mine  is  locally  known  as  the  Busch  mine. 
No  mining  has  been  done  here  for  several  years.  Atwood,  when  he 
visited  the  prospect  in  1907,  reported  that  the  slope  had  caved  so  as 
to  make  the  mine  inaccessible.  According  to  Collier,  at  the  time  of 
his  visit  in  1903 : 

In  the  tunnel,  which  extends  about  40  feet,  large  bodies  of  crushed  coal  4 
to  5 feet  in  thickness  are  exposed.  The  coal  is  regarded  as  bituminous,  having 
a fuel  ratio  of  1.76  and  a water  content  of  11.17  per  cent.  The  high  percentage 
of  water  is  probably  due  to  decomposition  of  the  coal  in  the  croppings.  No 
coal  has  been  produced.® 

Aanalysis  of  coal  from  Busch  mine,  ^ miles  beloic  Nulatof 
[Analyst,  E.  T.  Allen,  U.  S.  Geol.  Survey.] 


Moisture « 11. 17 

Volatile  matter 29.  48 

Fixed  carbon 52.  02 

Ash 7.  33 


100.00 

Sulphur . 44 

Fuel  ratio : 1.  76 

Coke,  noncoherent. 


About  5 miles  below  the  Busch  prospect  is  the  Blatchford  mine, 
which  is  also  abandoned.  Collier  reports : ° 

One  workable  coal  bed  has  been  opened  at  this  place.  This  bed-  has  been 
crushed  and  sheared  by  the  movements  of  the  inclosing  strata,  making  it  very 
irregular.  Large  masses  8 feet  in  diameter  have  been  found  and  mined  out, 
showing  that  before  it  was  disturbed  the  coal  bed  probably  had  considerable 
thickness.  The  coal  has  a tendency  to  break  up  into  fine  pieces,  though  it  is 


• Collier,  A.  J„  Bull.  U.  S.  Geol.  Survey  No.  213,  1903,  p.  281. 

b Collier,  A.  J.,  The  coal  resources  of  the  Yukon  : Bull.  U.  S.  Geol.  Survey  No.  218, 
1903,  p.  53. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


139 


a bituminous  coal  having  a fuel  ratio  of  3.30.  the  highest  of  any  coal  on  the 
Yukon,  and  a water  content  of  1.36  per  cent.  The  ash  is  only  2.22  per  cent, 
making  it,  by  approximate  analysis,  the  best  coal  seen  by  the  writer  on  the 
Yukon  River. 

This  mine  has  no  visible  development  or  permanent  equipment.  The  workings 
lie  below  the  level  of  the  river  and  the  entrance  is  covered  with  water  during 
the  summer  months,  so  that  it  can  be  worked  only  in  the  winter  after  the 
freezing  of  the  river,  where  the  ice  filling  the  upper  workings  must  be  mined 
out  before  the  coal  can  be  reached.  The  mine  has  probably  produced  about  300 
tons  of  coal. 

The  Williams  coal  mine  is  located  on  the  west  side  of  the  Yukon  just 
south  of  the  mapped  area.  It  has  been  more  extensively  developed 
than  any  of  the  mines  already  described,  but  as  it  does  not  come 
within  the  area  covered  by  this  report,  description  will  be  omitted 
except  to  state  that  in  a broad  way  conditions  are  the  same  there  as 
in  the  other  prospects. 

NORTON  BAY  BASIN  AND  SOUTHEASTERN  SEWARD  PENINSULA. 

Coal  has  been  reported  at  a number  of  places  along  the  eastern 
shore  of  Norton  Bay,  but  so  far  as  knowm  no  beds  of  a sufficient  size 
to  allow  profitable  mining  have  been  discovered.  Dali  mentions  a 
2-foot  bed  of  shale  and  lignite,  possibly  Kenai  in  age,  on  Ulukuk 
River,  a tributary  of  the  Unalaklik  from  the  north.®  It  was  reported 
to  have  no  commercial  value.  Brooks  & states : 

Capt.  D.  H.  Jarvis  informed  the  writer  that  some  very  good-looking  coal 
had  been  found  near  Unalaklik  Cape  near  the  eastern  shore  of  Norton  Sound. 
These  [beds]  probably  belong  to  the  same  §eries  described  by  Dali. 

Several  openings  have  been  made  near  the  mouth  of  the  Koyuk  on 
the  western  side  close  to  camp  BIT.  Unfortunately  the  shafts  were 
not  in  condition  to  be  examined,  and  the  only  information  gained  was 
from  a study  of  the  material  on  the  dump,  as  there  are  no  exposures 
of  the  coal-bearing  rocks  in  the  neighborhood.  Although  lignitic 
material  was  found  at  this  place,  several  years  of  desultory  prospect- 
ing have  failed  to  disclose  a workable  bed.  The  shafts  show  a series 
of  sandstones  and  clays  which  have  weathered  badly  on  the  dump 
and  appear  much  less  consolidated  than  the  average  sandstones  near 
Nulato.  It  is  understood  that  during  1909  the  company  formerly 
interested  in  this  claim  abandoned  the  enterprise. 

In  this  same  region  coal  float  has  been  found  on  Coal  Creek  and 
claims  have  been  recorded,  but  none  of  them  was  being  prospected  in 
1909.  Probably  little  of  value  was  found  as  the  series  is  without 
doubt  similar  to  that  near  camp  B17. 

* Dali,  W.  H.,  Correlation  papers,  Neocene : Bull.  U.  S.  Geol.  Survey  No.  84,  1892, 
p.  246. 

b Brooks,  A.  H.,  Coal  resources  of  Alaska  : Twenty-second  Ann.  Rept.  U.  S.  Geol.  Sur- 
vey, 1902,  pt.  3,  p.  560. 


140 


RECONNAISSANCE  IN  SEWARD  PENINSULA  AND 


Mendenhall a saj^s  concerning  his  investigation  in  southeastern 
Seward  Peninsula  : 

The  only  rocks  encountered  in  the  reconnaissance  likely  to  carry  coal  are  the 
sediments  supposed  to  be  of  Tertiary  age  outcropping  on  the  Tubutulik  and 
Koyuk  rivers  in  narrow  belts.  No  direct  evidence  of  the  presence  of  this 
mineral  was  secured  on  the  Koyuk,  but  along  the  river  bank  associated  with 
the  sandstone  outcrops  on  the  Tubutulik  are  numbers  of  small  pieces  of  bright 
compact  coal  seemingly  of  good  quality. 

The  presence  of  this  coal  float  has  long  been  known  to  prospectors 
but  so  far  no  beds  that  would  warrant  investigation  have  been  dis- 
covered. 

As  previously  stated  one  locality  was  visited  in  1909  where  there 
is  a woody  lignite  of  relatively  recent  age  and  differing  from  those 
previously  described.  This  exposure  is  on  the  Rathlatulik,  a tribu- 
tary of  Fish  River,  about  10  miles  above  the  junction  of  the  streams. 

A shallow  pit  has  been  sunk  here  and  slightly  carbonized  fragments 
of  wood  found.  Underneath  this  layer  of  woody  material  is  a black- 
ish-green calcareous  muck  which  is  nearly  flat  or  has  a slight  slope 
toward  the  east.  A cross  section  of  the  valley  at  this  point  shows  a 
low  bench  about  5 feet  above  the  water,  succeeded  on  the  east  by 
another  bench  15  feet  higher  100  paces  beyond  the  stream  and  sepa- 
rated from  the  lower*  bench  by  a steep  cliff.  All  the  material  from 
the  stream  to  the  top  of  the  15-foot  cliff  is  well-rounded  gravel. 
Several  abandoned  river  beds  are  found  on  the  lower  bench. 

The  coal  is  not  over  18  inches  thick  and  is  of  poor  quality,  having 
advanced  little  beyond  the  wood  stage.  Resin  is  abundant  in  many 
of  the  samples  of  this  material.  No  tests  of  the  coal  were  made, 
but  from  its  physical  character  it  does  not  seem  possible  that  it  could 
be  used  for  fuel  except  very  locally.  No  accurate  estimate  of  the 
amount  of  material  available  could  be  made  without  further  exploita- 
tion, but  it  is  believed  to  be  of  very  slight  extent  and  not  of  sufficient 
value  to  warrant  further  development. 

CONCLUSIONS  REGARDING  THE  COAL  RESOURCES. 

In  the  foregoing  paragraphs  the  places  where  the  coal-bearing 
rocks  have  been  prospected  to  some  extent  have  been  described  with 
the  object  of  showing  the  general  character  of  the  known  coal  depos- 
its. Indications  of  coal  have  been  noted  at  many  other  places,  but 
the  types  are  essentially  similar  and  do  not  merit  specific  description. 
There  are  certain  conclusions  that  may  be  drawn  from  the  facts  that 
may  save  prospectors  from  spending  their  time  unprofitably  in  the 
search  of  coal.  Coal  will  be  found  only  in  the  areas  of  Cretaceous 
sediments.  No  economically  important  beds  are  to  be  expected  in 

“Mendenhall,  W.  C.,  A reconnaissance  in  the  Norton  Bay  region,  Alaska,  in  1900,  a 
special  publication  of  the  U.  S.  Geol.  Survey,  1901,  p.  214. 


NORTON  BAY-NULATO  REGION,  ALASKA. 


141 


the  unconsolidated  alluviums  such  as  those  in  the  Fish  River  basin 
on  the  Rathlatulik.  From  the  fact  that  so  far  there  is  no  productive 
mining  on  any  of  the  coal-bearing  rocks  outcropping  along  the  Yukon 
within  the  mapped  area,  it  seems  improbable  that  workable  beds 
in  the  same  series  of  rocks  will  be  developed  in  the  immediate  future 
in  the  more  remote  regions  where  transportation  facilities  and  mar- 
kets are  wanting.  Although  thicker  beds  may  be  found  here  and 
there,  the  additional  cost  of  transportation  for  each  mile  that  the 
deposit  lies  back  from  the  river  or  from  some  other  cheap  avenue  of 
communication  increases  much  more  rapidly  than  the  thickness  of  the 
bed  could  be  reasonably  assumed  to  increase.  It  is  improbable,  there- 
fore, that  workable  coal,  where  it  is  not  now  known,  will  be  found  in 
the  Nulato-Council  area. 


INDEX. 


A.  Page. 

Acknowledgments  to  those  aiding 10-11 

Admiral  Creek.  See  Camp  Creek. 

Alameda  Creek,  gold  on 110-115 

gravel  on 81 

map  of 110 

rocks  on 53 

Albion  Gulch,  gold  of 121 

Anaconda  Creek,  gold  on 116 

Arvesta  Creek,  description  of 19 

Atwood,  W.  W.,  survey  by 16,57,59,60 

B. 

Baker  Creek,  moraine  on 84 

Bald  Head,  rocks  of 53, 54 

Basin  Creek,  gold  on 118 

Bear  Creek,  gold  placers  on 125-126 

gold  placers  on,  map  of 125 

gravel  on 80 

Bear  River,  rocks  on 73-74 

Bendeleben  Mountains,  character  of 29-30 

copper  in 135 

glaciation  in 83-84 

rocks  of 42-44,64,68-71 

veins  in 75 

Big  Bar  Creek,  gold  on 114 

Birch  Creek,  rocks  on 43, 69 

Bishop  Rock,  rocks  of 60 

Blatchford  mine,  coal  of 138-139 

Bluff,  gold  near. . . 123-125, 128-129 

gravels  at ’ 79 

lodes  near,  section  showing 129 

population  near 38 

rocks  near 61,63 

figure  showing 63 

Bluff-Topkok  Head  area,  rocks  of 52 

Bonanza  Creek,  placers  on 105-108 

rocks  near . . , 54, 55, 71 

working  methods  at 106-107 

Boston  Creek,  rocks  on 50 

Brooks,  A.  H.,  cited 52, 63, 82, 128, 139 

preface  by 7-8,15 

Brooks  divide,  character  of 29 

Buckland  River,  basin  of,  description  of 28 

basin  of,  gold  in 125-126 

rocks  of 67-68 

Busch  mine,  coal  of 138 

coal  of,  analysis  of 138 


C. 

Calcite  veins,  character  and  distribution  of . . 74 

Camp  Creek  (of  Niukluk),  gold  on 121-122 

Camp  Creek  (of  Tubutulik),  gold  on 115-116 

Candle  Creek,  gold  on 126-127 


Page. 

Caribou  Creek,  description  of \ 19-20 

Carson  Creek,  copper  near 134 

rocks  on 65 

Cheenik,  veins  near 75 

Christmas  Creek,  gold  on 108 

Christmas  Mountain,  faulting  at 89 

formation  of 98, 100 

placers  at 108-109 

rocks  of 54,70,105 

Chukajak  Creek,  gold  on 115 

Climate,  records  of 35-38 

Coal,  occurrence  and  character  of 136-141 

Coal  Creek,  coal  of 139 

rocks  on 53 

Coast,  features  of IS,  30-32, 78-79 

placers  on 102-105 

view  of 3C 

Collier,  A.  J.,  cited.  43, 69, 71, 73, 117-123, 128, 137-139 

work  of 16 

Concretions,  views  of 56 

Copper  prospects,  description  of 134-136 

Council,  population  near 38 

rocks  near 74 

Council  region,  gold  in 116, 117-123 

Cretaceous  rocks,  coal  in 136 

occurrence  and  character  of 39,54-60,97 

Cretaceous  time,  coast  in,  deposition  at 103-104 

conditions,  figure  showing 103 

events  in 96-97 

Crooked  Creek,  gold  on 120-121,128 

Cub  Creek,  gold  on 125 

D. 

Dali,  W.  H.,  work  of 14 

Daniels  Creek,  gold  lodes  on 128 

gold  placers  on 123-124 

map  of 123 

rocks  on 63 

section  of , figure  showing 63 

Darby  Peninsula,  coast  of,  inclusions  at, 

view  of..., 66 

coast  of,  view  of 30 

copper  in 134 

rocks  of 61, 62* 

section  of,  figure  showing 62 

views  of 46,66 

Darby  Range,  character  of 29-30 

glaciation  in 83-84 

effects  of,  view  of 30 

rocks  near 44-45, 46-49, 61, 62, 64-67 

section  of,  figure  showing 62 

structure  in 89-90 

veins  in 74, 75 

view  of 50 


143 


144 


INDEX. 


Page. 

Death  Valley,  gravels  in 82 

rocks  of 42, 46 

Devonian  time,  events  in 95 

Drainage,  basins  of,  description  of 18-32 

character  of 17-18 

relation  of,  to  geologic  structure 23,24 

figure  showing 23 

Dust  whirls,  occurrence  of 38 

Dutch  Creek,  gold  on 120 

E. 

Eakin,  H.  M.,  work  of 8 

Economic  geology,  account  of- 100-141 

Effusive  rocks,  character  and  distribution  oL  71-74 

deposition  of 94, 95, 98, ,100 

Eldorado  Creek,  gold  on 123, 125 

Elevations,  height  of 27, 28 

Elkhorn  Creek,  gold  on 122-123 

Erosion,  period  of 94, 98, 99, 100 

Eskimos,  homes  of 38-39 

Etchepuk  River,  description  of 27 

moraines  near 84 

rocks  near ■. ..  66 

Exploration,  history  of 12-17 

F. 

Faults,  occurrence  and  character  of 86-92, 100 

Field  work,  character  and  extent  of 7-8, 9-10 

Fish,  occurrence  of 35 

Fish  River,  basin  of,  coal  of 141 

basin  of,  description  of 25, 27 

gold  in 116-123 

gravel  in 82 

glacial  deposits  in 84,85 

gold  on 116,117 

rocks  on 43,49-51 

Folds,  diagram  showing 91 

occurrence  and  character  of 86-92, 100 

Forage,  occurrence  of 33 

Fox  Creek,  gold  on 47 

gravel  on 80 

rocks  on 44 

G. 

Galena,  occurrence  of 131 

Game,  character  of 33-35 

Geography  , description  of 11-32 

Geologic  history,  account  of 93-100 

diagrammatic  summary  of 100 

Geologic  maps  of  area Pocket. 

of  Omilak  region 44 

Geologic  structure,  effect  of,  on  drainage 23-24 

effect  of,  figure  showing 23 

Geology,  description  of 39-86 

Gisasa  River,  basin  of,  description  of 19 

Glacial  deposits,  character  and  distribution  of.  83-85 

Glaciation,  occurrence  of 99, 100 

effects  of,  view  of 30 

Goldbottom  Creek,  gold  on T. 122, 128 

Gold  lodes,  occurrence  and  character  of 128-130 

Gold  placers.  See  Placers. 

Golofnin  Bay,  description  of 31 

gravels  of 79 

Gravels,  character  and  distribution  of ...... . 78-83 

Greenstones,  character  and  distribution  of.. . 71-73 

deposition  of 94-95, 100 

Grouse  Creek,  rocks  on 73 


H.  Page. 

Harbors,  lack  of 18, 31 

Haystack  Mountain,  rocks  of 53 

Henshaw,  F.  F.,  cited 51,83,85,127 

Hills,  character  of 29 

character  of,  figure  showing 29 

Historical  geology,  account  of 93-100 

diagrammatic  summary  of 100 

History,  review  of 12-17 

I. 

Igneous  rocks,  character  and  distribution  of.  60, 74 

Iguik  River,  basin  of 21 

Inclusions,  view  of 66 

Indians,  homes  of 38-39 

Inglutalik  River,  basin  of,  description  of 20-21, 

23-24 

rocks  on  and  near 59 

view  of 58 

Intrusive  rocks,  character  and  distribution  of . 70-71 

deposition  of 94-95,96,100 

gold  associated  with 105 

Isaacs  Point,  rocks  of 53 

I.  X.  L.  Gulch,  gold  of 117 


Jurassic  time,  events  in. 


K. 

Kachauik  Creek,  rocks  on 45, 49, 67 

Kaiyuh  Hills,  rocks  of 40,61 

Kaltag,  rocks  near 71-72 

Kateel  River,  basin  of,  description  of 19-20 

Kennicott,  Robert,  exploration  by 14 

Kenwood  Creek,  gold  on 112-113 

rocks  on  or  near 41, 73 

Kindle,  E.  M.,  fossils  identified  by. 47,48 

Kiwalik  Mountain,  rocks  near 42, 46, 64, 67-68 

structure  in 90 

Kiwalik  River,  basin  of,  gold  in 126-127 

Kotzebue  Sound,  description  of 31 

drainage  to 18, 28 

explorations  near 13-14 

Koyuk  River,  basin  of,  description  of 24-25 

basin  of,  gold  in 104, 110-115 

gravel  in 80 

rocks  of 42, 46, 53, 54, 55, 68, 72-73, 88, 98 

channels  of 113 

gold  on 110 

rocks  on 54,71 

Kwik  River,  basin  of,  description  of 25 

basin  of,  gold  in 115 

rocks  of 41-42,45,55-56 

gold  near 104 

Kwiniuk,  Mount,  rocks  of  and  near 52,53,94 

Kwiniuk  River,  basin  of,  description  of. . . 25, 26-27 

basin  of,  gold  in 116 

rocks  on  and  near 46-50,65-66 

views  of 46,58 

L. 

Lead.  See  Silver-lead. 

Limestone,  folding  in,  views  of 50, 90 

intrusions  in,  views  of 46 

veins  in,  view  of 66 

Lindburg,  John,  aid  of H 

Little  Anvil  Creek,  gold  on 125 

Location  of  area,  description  of 11-12 

map  showing 12 


INDEX, 


145 


Page. 

Lodes,  occurrence  and  character  of 127 

See  also  Gold;  Copper;  Silver;  Lead. 

Lost  Creek,  rocks  on 47, 56 

Louden,  coal  at 136-137 

coal  at,  analysis  of 137 

M. 

McKelvie  Creek,  glacial  deposits  on 83 

McPherson,  J . L.,  cited 16, 115 

Maddren,  A.  G.,  survey  by 16-17, 40, 61 

Map,  index,  showing  area 12 

Maps,  Alaskan,  development  of 7-8 

Maps,  geologic,  of  area Pocket. 

of  Omilak  region 44 

Maps  of  area Pocket. 

description  of 11-12 

Marine  gravels,  age  of 86 

character  and  distribution  of 78-79 

Mastodon,  bones  of 23 

Melozitna  River,  rocks  on 57, 60 

Melsing  Creek,  gold  on 118 

rocks  on 50,84 

Mendenhall,  W.  C.,  cited 42-43, 

50-51, 54, 56, 64-65, 72, 73, 75, 
79,  82,  85,  114-115,  116,  140 

work  of 15-16 

Metamorphic  rocks,  gold  placers  in 109-127 

occurrence  and  character  of 39-46, 61-64 

Metamorphism,  occurrence  of 95 

Mineralization,  occurrence  of 95 

Miniatulik  River,  rocks  on 47 

Moffit,  F.  H.,  cited 42, 

67-68, 72-73, 92, 114, 115, 125, 126 

Moon,  Thomas,  aid  of 11 

Mosquito  Creek,  description  of 27 

Mountain  building,  periods  of 94-95, 97-98, 100 

Mukluktulik  River,  rocks  on 41, 53-54, 73 

Munro,  C.  H.,  acknowledgments  to 10-11 

Mystery  Creek,  gold  on 117-118 

gravel  on 80 

rocks  on 50 

N. 

Niukluk  River,  description  of 27 

gravel  on 81, 84 

rocks  near 44 

Nome,  gravels  at 86 

placers  at,  formation  of 101-102 

Norton  Bay,  coal  on 139 

rocks  on 72 

Norton  Bay  region.  See  Nulato-Norton  Bay 
region. 

Norton  Sound,  coasts  of 31-32 

drainage  to 20-27 

tides  in 31 

Noxapaga  River,  rocks  on 73 

Nulato,  gravels  near 81,83 

precipitation  at 37 

rocks  near 59-60 

settlement  of ' 13 

temperature  at 36 

Nulato-Norton  Bay  region,  definition  of 11-12 

geologic  map  of Pocket. 

section  of,  figure  showing 103 


See  also  Seward  Peninsula,  southeastern. 
71469°— Bull.  449—11 -10 


Page. 

Nulato  River,  basin  of,  description  of 20 

coal  near 137-138 

O. 

Omilak  Creek,  rocks  near 61 

silver-lead  on 130 

Omilak  mine,  deformation  near,  view  of 90 

fault  near 90-91 

geologic  map  of 44 

ore  of 131-133 

precipitation  at. 37 

production  of 132 

region  of,  view  of 50 

rocks  at 51-52, 63-64, 130-131 

figures  showing 50, 64 

settlement  at 38 

temperature  at 36 

workings  at 131 

Ophir  Creek,  folding  on 92 

folding  on,  view  of 90 

glacial  deposits  on 83 

gold  on 118-121,128 

gravel  on 81 

rocks  on 49 

Oregon  Creek,  moraine  on 87 

rocks  near 69 

P. 

Paleozoic  rocks,  deposition  of 94 

occurrence  and  character  of 46-54 

views  of 46 

Pargon  River,  description  of 27 

glacial  deposits  on 83-84, 85-86, 99 

gold  on 116 

Peace  River,  copper  on 135 

gold  on 114-115 

Peters,  W.  J.,  work  of 15 

Pickart  mine,  coal  of 137-138 

coal  of,  analyses  of 137 

Pinnacles,  views  of 30, 58 

Placers,  character  and  distribution  of. . 101, 109-110 

descriptions  of 105-109,110-127 

formation  of 101-105 

Population,  distribution  of 38-39 

Post-Cretaceous  igneous  rocks,  character  and 

distribution  of 61,70-74 

Pre-Cambrian  deposits,  occurrence  of 93-94 

Precipitation,  records  of 36-37 

Pre-Cretaceous  igneous  rocks,  character  and 

distribution  of 61-70 

Q. 

Quartz  Creek,  gold  on 115 


Quartz  veins,  character  and  distribution  of. . 74-76 


R. 

Rain.  See  Precipitation. 

Rathlatulik  River,  coal  on 140, 141 

description  of 27 

rocks  near 51 

Relief,  description  of 17,28-30 

origin  of 30 

Richardson,  G.  B.,  cited 122 

River  gravels,  character  and  distribution  of..  79-83 

Russell,  I.  O.,  cited 81,83 

survey  by 15 

Ryan  Creek,  gold  on 123, 125 


146 


INDEX, 


S. 


Page. 

St.  Michael,  founding  of 12-13 

Schists,  character  and  distribution  of 40-46 

Schrader,  F.  C.,  surveys  by 15, 16 

Settlements,  distribution  and  character  of . . . 38-39 

Seward  Peninsula,  coal  of 140 

rocks  of 40-46 

work  in,  completion  of 7-8, 9 

Seward  Peninsula,  southeastern,  definition 

of 12 

geologic  map  of Pocket. 

map  of Pocket. 

Shaktolik  group,  character  and  distribution 

of 55,57-60 

deposition  of 97, 100 

views  of 56,58 

Shaktolik  River,  basin  of,  description  of 20-22 

basin  of,  gravels  in 81 

valley  in,  view  of 22 

faults  in 89 

rocks  on 57-59, 60, 71 

view  of 56 

Sheridan  Creek,  gold  on 125 

Silver-lead  deposit,  description  of 130-133 

See  also  Omilak  mine. 

Smith,  P.  S.,  work  of. ...  1 8, 43 

Spits,  occurrence  and  character  of 32 

Spurr,  J.  E.,  cited 57,71,105 

survey  by 15 

Stibnite,  occurrence  of 108, 131 

Structural  geology,  description  of 86-93 

Surveys,  Alaskan,  development  of 7 

Swede  Gulch,  gold  on 123 

S wee tcake  Creek,  gold  on 119 


Temperature,  records  of 35-36 

Tertiary  time,  events  in 98-99 

Tides,  range  cf 31 

Timber,  character  of 32-33 

distribution  of,  map  showing 32 

Timber  Creek,  copper  on 134 

Topography,  description  of 17-32 


Transported  material,  character  and  distri- 


bution of 78-85 

types  of 77 

See  also  Marine,  River,  and  Glacial  de- 
posits. 

Traverse  Peak,  diagrammatic  section  at 87 

structure  near 87-88 

Tubutulik  River,  basin  of,  description  of 25-26 

basin  of,  gold  in 115-116 


rocks  in 46, 55-56, 88-89 


U. 

Tage. 

Ulrich,  E.  O.,  fossils  determined  by 48 

Ulukuk  River,  coal  on 139 

Unalaklik,  founding  of 13 

Unalaklik  River,  basin  of,  description  of 20-21 

Unconsolidated  deposits,  age  of 85-86 

occurrence  and  character  of 76-85 

See  also  Transported  and  Unsorted  de- 
posits. 

Ungalik  conglomerate,  character  and  distri- 
bution of 55-57,88 

deposition  of 97, 100 

Ungalik  River,  basin  of,  description  of. . 20-21, 22-23 

faulting  on 89 

gravel  on 78 

rocks  of 55-56,70-71 

Unsorted  deposits,  character  and  distribution 

of 76-77 

Uplands,  view  of 22 

See  also  Relief. 

Uplift,  evidence  of 78-79,82 

periods  of 94, 95, 97-98, 100 


Valley  topography,  view  of . . . •. 22 

Vegetation,  character  of 32-33 

Veins,  character  and  distribution  of 74-76 

formation  of 94,100 

view  of 66 

Vulcan  Creek,  gold  on 115 

W. 

Walla  Walla  Creek,  gold  on - 129 

Warm  Creek,  gold  on 122, 128 

Watkins,  J.  T.,  cited 72 

Williams  mine,  coal  of 139 

Willow  Creek,  gold  on 114 

Winds,  character  of 37-38 

Winegarden,  A.  G.,  work  of 9,10 

Y. 

Yukon  basin,  coal  in 136-139 

drainage  of 19-20 

rocks  of 40,71-72 

Z. 

Zagoskin,  L.  A.,  explorations  by 13,24 


O 


DEPARTMENT  OF  THE  INTERIOR 

UNITED  STATES  GEOLOGICAL  SURVEY 

GEORGE  OTIS  SMITH,  Director 


Bulletin  450 


MINERAL  RESOURCES 

OF  THE 

LLANO-BURNET  REGION,  TEXAS 

WITH 

AN  ACCOUNT  OF  THE  PRE-CAMBRIAN  GEOLOGY 


BY 

SIDNEY  PAIGE 


WASHINGTON 

GOVERNMENT  PRINTING  OFFICE 

1911 


CONTENTS. 


Page. 

Introduction • . . 7 

Topography # 8 

Drainage 8 

Geology... 9 

General  features 9 

Algonkian  (?)  rocks 9 

Geologic  units 9 

Granites 10 

Geologic  relations 10 

Types  and  distribution 11 

Petrography 11 

Coarse-grained  type 11 

Medium  to  line-grained  types  including  some  coarse  varieties . . 12 

Opaline  quartz-feldspar  porphyry  type 14 

Schists  and  gneisses  (Llano  series) 14 

Divisions  and  distribution 14 

Packsaddle  schist 15 

Distribution  and  general  character 15 

Petrography 17 

Valley  Spring  gneiss 19 

Distribution  and  general  character 19 

Petrography 20 

Origin  of  the  schists  and  gneisses 20 

Basic  intrusive  rocks  of  a gabbro-diorite  type 21 

General  character  and  distribution 21 

Petrography 22 

Paleozoic  rocks 23 

Upper  Cambrian  rocks 23 

Cambro-Ordovician  rocks 24 

Carboniferous  rocks =. 24 

Structure 25 

Iron  ores r 26 

General  description,  by  A.  C.  Spencer 26 

Special  localities 28 

Olive  property 28 

Bader  tract 31 

Iron  Mountain 34 

Keyser-Jones  tract 40 

Goodwin  prospect 41 

Parkhill  prospect 42 

Iron  deposits  near  Castell 42 

Deep  Creek  ores 42 

Elm  Creek  ores .r 45 

Lively  tract 48 

Section  13  and  vicinity 49 

Riley  Mountain 54 


3 


4 


CONTENTS. 


Iron  ores — Continued.  Page. 

Origin  of  the  iron  ores 56 

Possible  hypo  theses 56 

General  distribution  of  iron  throughout  geologic  formations  and  the 

character  of  the  accompanying  beds 56 

Geologic  relations  of  the  iron  ores 57 

Characteristics  of  the  ores 58 

Bearing  of  igneous  rocks  of  the  region  on  origin  of  iron  ore 60 

Chemical  relations 62 

Probable  conditions  at  time  of  intrusion 65 

Comparison  with  other  regions 68 

Summary 69 

Gold 70 

Copper 73 

Lead 75 

Graphite 77 

Manganese 82 

Rare-earth  metals 83 

General  description  of  the  deposit 83 

The  rare-earth  minerals 85 

Economic  value 88 

Zinc  blende  with  fluorite  gangue 89 

Serpentine  and  talc 90 

Oil 93 

Structural  materials 94 

Marble 94 

Sandstone 94 

Limestone 95 

Granite 95 

Index 101 


ILLUSTRATIONS. 


Page. 

Plate  I.  Geologic  map  of  Texas 7 

II.  General  geologic  and  economic  map  showing  locations  of  Burnet  and 

Llano  quadrangles,  Texas 8 

III.  Economic  and  geologic  map  of  llano  quadrangle,  Texas In  pocket 

IV.  A,  Assimilation  of  schist  fragment  along  borders  at  contact  with 

granite;  B,  Banding  of  magnetite  ore 10 

V.  A,  Folding  of  Upper  Cambrian  sandstone  on  Beaver  Creek,  near  lead 

prospect;  B,  Pegmatite  and  granite  intruding  schist 76 

Figure  1.  Local  flowage  of  schist  at  granite  contact 10 

2.  Cross  section  and  plan  of  Olive  mine 30 

3.  Distribution  of  float  and  outcrops  on  Bader  tract  and  vicinity 32 

4.  Surface  crop  and  underground  workings  at  Iron  Mountain  prospect.  35 

5.  Vertical  section  of  ore  body  at  Iron  Mountain  prospect 36 

6.  Ideal  section  showing  relation  of  faulting  to  folding  and  erosion. . . 37 

7.  Stereogram  illustrating  condition  which  would  exist  if  the  north 

fault  passed  vertically  but  at  an  angle  to  the  strike  of  the  fold. . 38 

8.  Magnetite  prospects  on  Keyser-Jones  tract,  southwest  of  Castell. . . 40 

9.  Distribution  of  magnetite  near  Deep  Creek 43 

10.  Distribution  of  magnetite  near  Elm  Creek,  northeast  of  Castell 45 

11.  Distribution  of  magnetite  showings  in  northern  part  of  Schneider’s 

pasture 47 

12.  Distribution  of  magnetite  2 miles  east  of -Castell 49 

13.  Magnetite  prospects  in  H.  & G.  N.  Section  13 50 

14.  Relation  of  ore  layers  in  pit  south  of  Willow  Creek  in  section  13.  . 51 

15.  Sketch  of  8-foot  ore  surface  in  magnetite  gneiss 52 

16.  Map  showing  location  of  pyrite  deposits  north  of  Click  post-office 

and  their  relations  to  faults 54 

17.  Concentration  of  magnetite  along  edges  of  schist  fragment  at  granite 

contact 61 

18.  Remnant  of  schist  fragment  in  granite  mass 62 

19.  Prospect  pits  and  shafts  at  Heath  gold  prospect 72 

20.  Map  showing  location  of  lead  prospects  north  of  Bluff  ton  and  area 

covered  by  figure  21 75 

21.  Plan  and  ideal  section  showing  relations  of  Upper  Cambrian  to 

underlying  pre-Cambrian  granite  at  lead  prospects  north  of 
Bluffton 76 

22.  Plan  of  workings  at  graphite  property  near  Lone  Grove 79 


5 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  450  PLATE  I 


GEOLOGIC  MAP  OF  TEXAS. 

See  page  7. 


BULLETIN  450  PLATE  I 


Tertiary  and 
later  effusives 


MINERAL  RESOURCES  OF  THE  LLANO-BURNET  REGION, 
TEXAS,  WITH  AN  ACCOUNT  OF  THE  PRE-CAMBRIAN 
GEOLOGY. 


By  Sidney  Paige. 


INTRODUCTION. 

The  field  work  on  which  the  following  report  is  based  was  begun  in 
the  summer  of  1908  under  the  direction  of  A.  C.  Spencer,  who  was 
assisted  by  the  writer,  and  was  completed  in  the  fall  of  1909  under  the 
direction  of  the  writer,  who  was  assisted  by  Fred  H.  Kay.  A.  C. 
Spencer  and  W.  S.  Bayley  cooperated  in  the  field  work,  and  Mr. 
Spencer  has  contributed  descriptions  of  certain  of  the  iron-ore  de- 
posits. Howland  Bancroft  also  spent  a short  time  in  the  field.  A 
general  report  on  the  Llano  and  Burnet  quadrangles,  to  be  pub- 
lished in  folio  form,  is  now  in  preparation.®  The  present  report  deals 
chiefly  with  the  geologic  relations  of  the  pre-Cambrian  rocks  and  the 
associated  iron  ores.  The  stratigraphic  and  structural  relations  of 
the  Paleozoic  and  Cretaceous  rocks  are  only  briefly  treated,  but  will 
be  discussed  more  fully  in  the  later  report.® 

The  writer  wishes  to  express  his  indebtedness  to  Dr.  Spencer, 
whose  acquaintance  with  pre-Cambrian  structure  and  iron  ores  has 
been  of  great  value  in  both  the  field  and  the  office  work.  Thanks  are 
due  also  to  Prof.  W.  S.  Bayley  for  counsel  and  suggestion,  and  to  Mr. 
N.  J.  Badu,  of  Llano,  whose  knowledge  of  Llano  County  was  of  great 
assistance  during  the  field  work. 

The  central  Texas  region  lies  in  the  broad  regional  coastward  slope, 
of  which  Texas  forms  a part  and  which  constitutes  a great  geologic 
province  reaching  from  the  Cordilleras  to  the  Gulf  of  Mexico.  (See 
PI.  I.)  In  this  region,  about  midway  between  the  Cordilleras  and  the 
Gulf  the  peculiar  condition  exists  that  erosion  has  exposed  rocks  of 
pre-Cambrian  and  Paleozoic  ages  within  and  about  the  rim  of  an  oval 
structural  and  topographic  basin  which  is  nearly  surrounded  by  Cre- 
taceous rocks  on  its  outer  border.  This  area  of  old  rocks  is  largely 
included  in  the  Llano  and  Burnet  quadrangles.  (See  PI.  II.) 


Paige,  Sidney,  Llano-Burnet  folio,  Geol.  Atlas  U.  S.,  U.  S.  Geol.  Survey.  (In  preparation.) 


8 MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

As  the  principal  mineral  resources  of  the  region  are  confined  largely 
to  the  Llano  quadrangle,  this  report  deals  almost  entirely  with  that 
area. 

The  Llano  quadrangle  includes  portions  of  Llano,  Mason,  and  San 
Saba  Counties  in  central  Texas.  (See  PI.  Ill,  in  pocket.)  It  is 
bounded  by  parallels  30°  30'  and  31°  and  meridians  98°  30'  and  99° 
west,  and  covers  1,024  square  miles.  The  region  is  accessible  by  the 
Houston  & Texas  Central  Railroad,  which  terminates  at  Llano,  the 
county  seat  of  Llano  County.  This  road  connects  at  Lampasas,  about 
20  miles  north  of  Burnet,  Burnet  County,  with  the  Gulf,  Colorado, 
& Santa  Fe  Railway.  Llano  is  the  principal  town  of  the  quadrangle. 

TOPOGRAPHY. 

A casual  observer,  standing  on  an  eminence,  such  as  Town  Moun- 
tain, near  Llano,  will  be  impressed  with  the  basin-like  form  of  the  broad 
valley  of  Llano  River.  From  such  an  eminence  a broad  rolling  plain 
may  be  seen  stretching  east,  west,  north,  and  south  to  the  horizon, 
which  is  marked  by  an  encircling  scarp  of  Paleozoic  rocks.  Within 
this  broad  area,  however,  there  are  many  minor  irregularities. 
These  irregularities  are  of  two  types — first,  mountain-like  masses, 
such  as  Riley,  Packsaddle,  Putnam,  House,  and  Smoothingiron  Moun- 
tains; and  second,  smaller  masses,  such  as  the  group  of  hills  west  of 
Oxford  and  that  northeast  of  Babyhead,  as  well  as  the  many  isolated 
hills  north  and  south  of  Llano.  The  masses  of  the  first  type  are  char- 
acterized by  cappings  of  nearly  horizontal  beds  and  steep  marginal 
scarps,  and  present  to  the  observer  mesa-like  outlines;  those  of  the 
second  type  are  maturely  dissected  hills  and  isolated  cones  that  rise 
rather  abruptly  from  the  surrounding  plains.  The  form  of  the  masses 
of  both  types  depends  on  the  nature  of  the  rocks  composing  them. 
Encircling  the  pre-Cambrian  basin  described  above  is  a plateau  of 
Paleozoic  and  Cretaceous  rocks,  more  or  less  maturely  dissected.® 

The  northern  border  of  the  Llano  quadrangle  lies  within  the  Pale- 
ozoic plateau;  its  western  part  is  a rolling  plain,  which  to  the  east 
and  approaching  Colorado  River  becomes  more  broken  and  irregular. 
The  Paleozoic  scarp  to  the  west  and  south  does  not  lie  within  the 
Llano  quadrangle. 

DRAINAGE. 

The  region  included  in  the  Llano  quadrangle  is  drained  almost 
entirely  by  Llano  River  and  its  northward  and  southward  flowing 
tributaries.  The  quadrangle  is  nearly  halved  by  Llano  River,  which 
flows  eastward  across  it  and  enters  Colorado  River  at  Kingsland,  in 
the  Burnet  quadrangle. 


a Fo"  a detailed  classification  of  Texas  plateaus  see  Hill,  R.  T.,  Physical  geography  of  the  Texas  region: 
Top.  Atlas  U.S.,  folio  3,U.  S.  Geol.  Survey,  1900;  Geography  and  geology  of  the  Black  and  Grand  prairies, 
Texas:  Twenty-first  Ann.  Rept.  U.  S.  Geol.  Survey,  pt.  7,  1901. 


LEGEND 

SEDIMENTARY  ROCKS 


Cretaceous 


Paleozoic 

METAMORPHIC  AND 
IGNEOUS  ROCKS 


Algonkiaii.(?) 


ISTote:  Dotted  boundaries 
are  only  approximate 
West  ofTneridian  9 9° they 
carvTvot be pLaee.fi on  the 
Trvap 


9i 


Qiiarry 


x 


Mine  and  prospect 


1 . Barringer  Hill 

la.  Fergusonite  and  gadolimte 

lb.  Gadolinite  in  pegmatite 

lc.  Allanite  and  fluorite 

2.  Magnetite 

2a.  Iron  Mountain  prospect 
2b.  Olive  mine 

3.  Heath  gold  prospect 

4.  Graphite  prospect 

5.  Serpentine  and  talc 

6.  Talc 

7.  Lead-galena 

8.  Pyrite  bodies 


logy  within  Llano  and  Burnet  auadrangles  by 
. Spencer,  Sidney  Paige,  W.  S.  Bayley,  and 
i H.  Kayr  Dotted  boundaries  compiled  from 
s by  Robert  T.  Hill. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  450  PLATE 


j'SAHA 


ndyviQ* 


Killeen 


lakalb 


Nea-un^L* 


Sunuyiane.  J 


Florence 


Fsbots 


.Gabriel 
\ Mills 


JvlASONN 


liberty  HiLL 


H rpewell 


Click 


Doublr 


"Vblenl 


.Jqyvflk 


fetteri 


^Cedin' 


Delvalle 


LEGEND 

SEDIMENTARY  ROCKS 


Cretaceous 


Paleozoic 

METAMORPHIC  AND 
IGNEOUS  ROCKS 


AlgonMam  ?) 


Note:  Dotted,  boundaries 
are  only  approanmate 
Westof‘nierxciian99'‘tht*y 
cojv  not  be  placed  on  the 


Quarry 


Mine  and.  prospect 


1.  Barringer  Hill 

la.  Fergusonite  and  gadolinite 

lb.  Gadolinite  in  pegmatite 

lc.  Allanite  and  fluorite 

2.  Magnetite 

2a.  Iron  Mountain  prospect 
2b.  Olive  mine 

3.  Heath  gold  prospect 

4.  Graphite  prospect 

5.  Serpentine  and  talc 

6.  Talc 

7.  Lead-galena 

8.  Pyrite  bodies 


GENERAL,  GEOLOGIC  MAP  SHOWING  LOCATIONS  OF  BURNET  AND  LLANO 

With  principal  quarries,  mines,  and  prospects 

Scale  "750000’ 


QUADRANGLES,  TEXAS 

Geology  within  Llano  and  Burnet  Quadrangles  by 
A.  C.  Spencer,  Sidney  Paige,  W.  S.  8ayley.  and 
Fred  H.  Kayr-  Dotted  boundaries  compiled  from 
maps  by  Robert  T.  Hill. 


20 


3oMiles 


1910 


GEOLOGY. 


9 


On  the  north,  Elm,  San  Fernando,  Johnson,  Pecan,  and  Mitchell 
Creeks  and  Little  Llano  River  are  the  important  affluents  of  Llano 
River;  on  the  south,  Hickory,  Bullhead,  Sixmile,  Flag,  Oatman,  and 
Honey  Creeks  are  the  large  streams.  Sandy  Creek,  in  the  southern 
part  of  the  quadrangle,  an  exception,  flows  eastward  into  the 
Colorado. 

Nearly  all  the  streams  of  the  region  within  the  pre-Cambrian  basin 
carry  a great  and  increasing  burden  of  sand.  During  most  of  the 
year  their  beds  are  apparently  dry,  and  it  is  only  by  digging  that 
water  can  be  found.  Llano  and  Little  Llano  Rivers  and  a few  other 
spring-fed  streams  are  exceptions.  The  infrequent  but  torrential 
rains,  the  stripping  of  the  granite  areas  of  vegetation  by  the  over- 
stocking of  ranches,  the  alternation  of  intense  heat  by  day  and  of 
coolness  by  night,  which  tends  to  disintegrate  the  rocks,  all  combine 
to  bring  about  this  condition  of  the  streams. 

GEOLOGY. 

GENERAL  FEATURES. 

The  rocks  of  the  Llano-Burnet  region  fall  naturally  into  three  broad 
subdivisions — (1)  pre-Cambrian  schists,  gneisses,  and  granites;  (2) 
Paleozoic  sandstones,  limestones,  and  shales;  and  (3)  Cretaceous 
sandstones,  clays,  and  limestones.  The  Cretaceous  rocks  are  con- 
fined almost  entirely  to  the  Burnet  quadrangle,  and  appear  in  the 
Llano  quadrangle  in  but  one  small  area. 

The  Paleozoic  strata,  which  completely  surround  the  pre-Cambrian 
area,  are  more  or  less  folded  and  faulted,  and  are  separated  from  the 
pre-Cambrian  by  an  unconformity  representing  a great  time  interval. 
The  Cretaceous  formations  rest  in  almost  undisturbed  position  on  the 
Paleozoic  rocks,  but  are  separated  from  them  by  a great  erosional 
unconformity. 

ALGONKIAN  (?)  ROCKS. 

GEOLOGIC  UNITS. 

Pre-Cambrian  rocks  underlie  the  larger  part  of  the  Llano  quad- 
rangle. A strip  along  the  northern  edge,  however,  ranging  in  width 
from  3 to  10  miles,  and  Riley  and  Cedar  Mountains,  Putnam  Moun- 
tain, and  a few  other  isolated  areas  are  covered  by  Paleozoic  sedi- 
ments. In  the  geologic  mapping  of  the  area -(see  PL  III)  four  major 
divisions  of  pre-Cambrian  rocks  have  been  discriminated,  namely, 

(1)  the  Packsaddle  schist,  a series  predominantly  of  basic  type,  includ- 
ing amphibolite  and  mica  schists  and  old  basic  intrusive  rocks; 

(2)  the  Valley  Spring  gneiss,  a schist-gneiss  series,  including  quartzites 
or  their  derivatives,  light-colored  mica  schists,  and  acidic  gneisses; 

(3)  a very  coarse  grained  pink  granite,  which  could  not  be  separately 
mapped  over  the  area;  (4)  all  the  remaining  granitic  rocks,  including 


10  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

a number  of  varieties.  All  these  rocks  are  believed  to  be  of  Algon- 
kian(  ?)  age.  In  addition  to  these  major  distinctions,  bands  of  crys- 
talline limestone  and  wollastonite  were  mapped  wherever  possible. 
Likewise  the  outcrops  of  a quartz  porphyry  of  peculiar  type,  locally 
termed  opaline  granite,  have  been  indicated,  and  a serpentine  mass 
near  Oxford  has  been  shown.  Iron-ore  prospects  and  some  lean 
banded  ores  are  also  represented.  The  area  surrounding  the  Llano- 
Burnet  region  is  shown  on  a general  map  (PL  II),  on  which  the 
several  economic  resources  are  indicated. 

A glance  at  the  map  forming  Plate  III  (in  pocket)  will  show  clearly 
in  a general  way  the  northwest-southeast  trend  of  the  schist-gneiss 
series;  also  the  complicated  and  irregular  distribution  of  the  granitic 
intrusive  rocks. 

GRANITES. 

GEOLOGIC  RELATIONS. 

The  granite  in  this  area  is  invariably  intrusive  and  is  almost  omni- 
present. It  cuts  the  schist  series  in  large  and  small  masses,  in  dikes, 
in  sills,  and,  if  pegmatite  may  be  considered  a phase  of  granite,  it  is 

found  both  in  minute 
veinlets  and  in  huge  dikes 
and  sheets.  The  area  con- 
tains rock  of  every  grade 
between  pure  granite  and 
pure  schist.  Certain  local- 
ities are  characterized  by 
pure  granite  masses  of 
batholithic  type,  such  as 
the  area  of  coarse  granite 
in  the  southwestern  portion  of  the  quadrangle,,  the  area  immediately 
west  of  Cedar  Mountain,  and  the  area  east  of  Lone  Grove.  Other 
areas  show  an  intimate  mixture  of  granite  and  schist,  the  schist 
being  literally  the  sponge  which  has  soaked  up  and  become  perme- 
ated with  granitic  material.  Such  permeation  is  best  developed 
about  the  edges  of  the  large  granitic  masses,  though  not  at  all 
confined  to  those  bodies.  (See  PI.  Y,  B,  p.  76.) 

The  manner  in  which  intrusion  was  effected  varied.  In  some 
places  portions  of  the  schists  were  in  a plastic  state  and  flowed  under 
the  influence  of  pressure  (see  fig.  1 ) ; at  other  localities  the  contacts 
of  the  cutting  dikes  are  sharp,  indicating  a condition  of  considerable 
rigidity;  elsewhere  the  temperature  of  the  intruding  mass  was  so  high 
that  masses  of  the  schist  lost  their  identity  and  passed  by  gradual 
melting  into  solution  (see  PL  IV,  A;  also  fig.  18,  p.  62) ; and  elsewhere, 
again,  granitic  material,  following  planes  of  least  resistance,  forced 
itself  between  the  layers  of  the  schists  and  formed  injection  gneisses. 


Figure  1.— Local  flowage  of  schist  at  granite  contact. 
a,  Schist;  b,  granite. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  450  PLATE  IV 


A.  ASSIMILATION  OF  SCHIST  FRAGMENT  ALONG  BORDERS  AT  CONTACT  WITH  GRANITE. 

See  page  1 0. 


B.  BANDING  OF  MAGNETITE  ORE, 
See  page  58. 


GEOLOGY. 


11 


The  results  of  the  processes  outlined  above  may  be  seen  both 
on  a small  and  on  a huge  scale,  and  afford  a fine  example  of  the 
conditions  existing  about  the  borders  of  a great  batholithic  mass  that 
lies  in  contact  with  a deeply  buried  sedimentary  series. 

The  dikes,  sills,  and  broader  masses  of  pegmatite,  which  occur  in 
great  abundance  and  in  all  sizes,  are  worthy  of  special  mention,  par- 
ticularly the  broader  masses,  which  are  locally  developed  at  contacts 
of  schist  with  crosscutting  granite  dikes.  In  the  areas  about  Hog 
Mountain  such  sheets  are  finely  developed,  and  it  is  believed  that 
they  indicate  the  proximity  of  schists  now  removed  by  erosion. 

TYPES  AND  DISTRIBUTION. 

Three  types  of  granite  have  been  distinguished  on  the  geologic  map — 
(1)  a very  coarse  grained  homogeneous  rock;  (2)  a medium  to  fine 
grained  granite,  including  some  coarse-grained  varieties;  and  (3)  an 
opaline  quartz-feldspar  porphyry.  Microscopic  examination  has 
shown  that  the  distinction  is  largely  textural,  the  mineralogical  con- 
stituents in  the  three  types  being  essentially  the  same. 

The  coarse-grained  granite  has  been  mapped  in  two  areas — one  in 
the  southwest  corner  of  the  quadrangle,  a large  subcircular  area  with 
Prairie  Mountain  as  a center;  the  other  farther  north,  in  the  vicinity 
of  Smoothingiron  Mountain.  Granite  of  the  same  type  occurs  east 
and  southeast  of  Lone  Grove  and  in  other  localities,  but  in  areas  so 
small  that  it  could  not  be  consistently  differentiated  in  mapping. 
Conclusive  evidence  in  regard  to  the  relative  age  of  this  coarse  granite 
was  not  discovered,  but  tentatively  it  may  be  considered  intrusive  in 
the  finer-grained  granites. 

The  granite  of  the  second  type,  the  widespread  dominant  rock  of 
the  region,  includes  various  textural  types,  ranging  in  texture  from 
very  coarse  to  very  fine  grained,  but  has  been  mapped  as  a unit. 

The  granitic  rock  of  the  third  type,  the  opaline  quartz-feldspar 
porphyry,  invariably  occurs  as  a dike  rock  cutting  both  the  schists 
and  the  intrusive  granites  which  accompany  them.  Its  outcrop  may 
be  followed,  with  interruptions,  from  a point  about  3J  miles  east  of 
Llano,  on  the  Llano-Lone  Grove  road,  northward  through  Miller 
Mountain  for  6J  miles,  where  it  bends  to  the  northeast  and  forms  a 
hook  passing  around  the  town  of  Babyhead  and  ending  about  a 
mile  southwest  of  that  place. 

PETROGRAPHY. 

COARSE-GRAINED  TYPE. 

The  very  coarse  grained  granite  is  of  reddish  tone,  due  to  the  large, 
finely  developed  potash  feldspars,  the  largest  an  inch  long  and  three- 
fourths  of  an  inch  broad,  the  average  length  being  perhaps  half  an 
inch.  The  space  between  these  well-crystallized,  finely  developed 


12  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION , TEXAS. 


crystals  is  filled  with  quartz.  Biotite,  the  dominant  ferromagnesian 
mineral,  is  well  developed  in  stout  columns  and  rather  abundant. 
Locally  a parallel  arrangement  of  the  large  feldspars  was  noted  in  the 
vicinity  of  Bullhead  Mountain,  a phenomenon  probably  due  to  move- 
ment under  pressure  while  the  magma  was  yet  in  a more  or  less 
viscous  state. 

A microscopic  examination  shows  the  following  characteristics: 

Very  coarse  granite  from  Watch  Mountain,  near  Walnut  Springs:  Feldspars  are 
microcline,  orthoclase,  and  albite-oligoclase.  Microcline  dominant.  Length  one-half 
inch  to  1 inch  or  more,  width  one-fourth  to  one-half  inch.  Quartz  filling  space  be- 
tween feldspars.  Biotite  mica  abundant  in  stout  columns  one-eighth  inch  or  more  in 
length.  Perthitic  intergrowth  of  microcline  and  albite  noted. 

MEDIUM  TO  FINE  GRAINED  TYPES,  INCLUDING  SOME  COARSE  VARIETIES. 

The  granites  mapped  under  this  head  include  many  varieties,  from 
fine  to  coarse  grain,  but  are,  in  general,  chemically  and  mineralogi- 
cally  similar.  Differences  of  texture  and  variations  in  the  quantity 
of  the  ferromagnesian  minerals  account  for  most  of  the  varieties. 

An  examination  of  numerous  specimens  reveals  an  abundance  of 
microcline,  with  orthoclase,  albite-oligoclase,  biotite,  quartz,  and  horn- 
blende. The  granites  are  distinctly  potash  rocks,  though  they 
almost  invariably  contain  soda.  They  also  contain  the  usual  acces- 
sory minerals — magnetite,  apatite,  titanite,  etc.  Several  hornblende 
granites  were  noted,  but  their  areal  extent  is  small. 

Petrographic  notes  made  on  granites  of  the  medium  to  fine  grained 
type  are  given  below : 

Granite  from  Parkinson  group  of  quarries. 

Megascopic  character. — Medium-grained  to  fine-grained  gray  granite . Biotite,  quartz, 
and  feldspar.  Mica  evenly  distributed  in  fine  flakes. 

Microscopic  character. — Largely  composed  of  microcline  with  subsidiary  orthoclase, 
rare  plagioclase.  Micrographic  intergrowth  with  quartz  in  some  feldspar.  Rare  zonal 
arrangement.  Alteration  has  set  in  on  nearly  all  the  feldspar.  Quartz  shows  some 
strain  phenomena.  Biotite  occasionally  altered  to  chlorite.  Alteration  of  feldspar 
more  pronounced  at  center  than  elsewhere.  Grain  or  two  of  magnetite. 

Granite  from  Kansas  City  quarry , 2 miles  west  of  Llano. 

Megascopic  character. — Medium  to  coarse  grained  light-gray  granite  with  slightly 
gneissoid  aspect.  Quartz,  feldspar,  mica. 

Microscopic  character. — Thirty-two  per  cent  quartz;  62  per  cent  feldspar,  microcline, 
and  orthoclase;  6 per  cent  mica  (biotite)  with  rare  muscovite;  71  per  cent  Si02.  Micro- 
graphic intergrowths  of  quartz  and  feldspar  occasionally  finely  developed. 

Hornblende  granite  from  northwest  Hog  Mountain , near  Wollastonite  rock. 

Megascopic  character. — Pinkish  toned  medium  crystalline  granular,  spotted  with 
blotches  of  hornblende  of  various  sizes  up  to  one-fourth  inch  in  diameter.  Ground- 
mass  between  the  blotches  is  barren  of  ferromagnesian  minerals. 


GEOLOGY. 


13 


Microscopic  character. — Microcline,  orthoclase,  and  albite-oligoclase  feldspars  domi- 
nant in  order  named.  Dark-green  hornblende  apparently  poikilitically  arranged 
about  quartz.  Measurements  with  microscope  show  31  per  cent  quartz,  69  per  cent 
feldspar,  75  per  cent  Si02. 

Granite  from  Norton  quarry. 

Megascopic  character. — Light-gray  granite;  abundant  mica  in  very  small  flakes, 
evenly  distributed. 

Microscopic  character . — Microcline,  orthoclase,  and  little  albite-oligoclase;  quartz 
abundant.  Biotite  mica. 

Red  granite  from  Parkinson’s  quarry  11  well  f'  camp  No.  1. 

Megascopic  character. — Red,  fine-grained  granite,  with  ferromagnesian  minerals  scant 
and  in  very  small  particles. 

Microscopic  character. — Microcline,  orthoclase,  and  albite-oligoclase  rather  abundant. 
Quartz  abundant.  Little  magnetite,  mica,  titanite,  and  hornblende.  Ferromag- 
nesian minerals  very  scant.  Feldspars  where  altered  are  replaced  by  a red  decom- 
position product. 

Granite  from  Grays  Mountain. 

Megascopic  character. — Coarse  pinkish  granite.  Feldspars  as  large  as  one -fourth 
inch  in  length  and  mica  very  abundant;  sufficient  to  give  dark  tone  to  rock. 

Microscopic  character. — Oligoclase  and  microcline.  Former  dominant.  Both  dom- 
inant over  quartz.  Biotite  abundant,  but  not  evenly  distributed.  Apatite.  Feldspar 
altered. 

Hornblende  granite  (a  chip  only)  from  south  edge  of  quadrangle  near  small  creek  above  house 

in  Elver’s  pasture. 

Coarse  granite.  Orthoclase,  microcline,  and  oligoclase  feldspars.  Quartz.  Horn- 
blende, partly  altered  to  chlorite.  Feldspars  badly  altered.  Zircon.  Apatite 
abundant.  Titanite. 

Pink  granite  from  west  of  road , east  of  direct  route  from  Castell  to  Berry  Spring  ( Goodes 

Spring ). 

Megascopic  character. — Fine-grained  pink  granite,  containing  circular  areas  im- 
poverished of  ferromagnesian  minerals,  in  the  center  of  which  are  aggregations  of 
titanite  and  magnetite. 

Microscopic  character. — Microcline,  orthoclase,  and  albite-oligoclase  feldspars  with 
biotite,  and  segregations  of  magnetite  and  titanite.  Part  of  the  quartz  one  of  the  first 
minerals  to  separate  out.  Apatite  needles  abundant. 

Granite  from  Heine’s  well , south  of  Willow  Creek,  4 miles  north  of  river,  1 mile  west  of  San 

Fernando  Creek. 

Megascopic  character. — Red  granite,  medium  to  fine  grain,  glassy  aspect. 
Microscopic  character. — Microcline  and  orthoclase  feldspars  and  quartz.  Microcline 
and  orthoclase,  badly  altered.  Scanty  biotite;  chloritized.  Sericite  developed  in 
feldspars.  Red  tone  very  probably  accentuated  by  alteration. 

Pink  granite  from  one-fourth  mile  west-northwest  of  Esbon  post  office  on  Kings  Mountain. 

Megascopic  character. — Fine-grained,  light-pink  granite,  ferromagnesian  minerals 
evenly  distributed  in  tiny  flakes. 

Microscopic  character. — Microcline  feldspar  dominant;  with  orthoclase  and  quartz. 
Biotite  (about  average  amount)  in  small  flakes.  Apatite  needles.  Feldspar,  espe- 
cially orthoclase,  badly  altered,  though  the  hand  specimen  looks  fresh. 


14  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


Granite  from  breast  of  crosscut  in  shaft  at  Iron  Mountain  (1908). 

Megascopic  character. — Pink,  medium  to  fine  grained  granite. 

Microscopic  character. — Microcline,  orthoclase,  and  albite-oligoclase  feldspars. 
Quartz.  Biotite  mica.  Little  magnetite. 


OPALINE  QUARTZ-FELDSPAR  PORPHYRY  TYPE. 


This  rock,  as  its  name  indicates,  is  a quartz-feldspar  porphyry. 
When  rough  in  the  hand  specimen,  it  has  a dark-reddish  aphanitic 
groundmass  mottled  with  abundant  phenocrysts  of  pink  feldspar 
and  opaline  quartz,  the  quartz  being  very  prominent  on  weathered 
surfaces.  The  quartz  phenocrysts  break  with  a glassy  fracture,  are  of 
liglit-bluish  tone,  and  possess  a certain  iridescence  when  polished. 
The  microscope  shows  quartz  phenocrysts  (with  a great  number  of 
minute  inclusions);  microcline  feldspar  phenocrysts;  microperthite 
phenocrysts  (albite  and  orthoclase);  a groundmass  of  quartz  and 
orthoclase,  and  small  flakes  of  biotite  mica;  a little  magnetite  with 
associated  sphene;  some  fine  zircons;  little  apatite;  local  chloritiza- 
tion  of  mica. 

Dr.  Joseph  P.  Iddings  proposed  the  name  of  llanite  for  this  rock 
some  years  ago.®  It  is  known  in  Llano  County  as  opaline  granite. 
Dr.  Iddings  ° estimated  that  the  rock  is  probably  composed  as  fol- 
lows: 

Mineral  composition  of  opaline  granite , Llano  County , Tex. 


Quartz... 
Feldspar. 
Biotite . . 
Fluorite. 
Apatite . 


34.6 

55.7 
8.6 
i 

.13 


In  speaking  of  the  bluish  color  of  the  quartz  he  says: 

The  sky-blue  milky  color  of  the  quartz  phenocrysts  is  undoubtedly  due  to  reflec- 
tion of  blue  light  waves  from  the  minute  colorless  prisms  whose  width  is  a fraction 
of  the  length  of  light  waves.  It  is  similar  to  the  blue  color  of  the  sky.  It  is  probable, 
however,  that  there  is  also  blue  light  produced  by  interference  of  the  light  reflected 
from  both  sides  of  the  minute  tabular  crystals,  whose  thickness  is  also  of  the  order 
of  a fraction  of  a light-wave  length.  So  that  both  kinds  of  phenomena  occur  within  the 
quartzes. 

SCHISTS  AND  GNEISSES  (LLANO  SERIES). 

DIVISIONS  AND  DISTRIBUTION. 


The  schists  and  gneisses  of  this  area  comprise  the  Llano  series,  and 
all  are  believed  to  be  of  Algonkian  age.  Two  broad  divisions  may 
be  recognized  and  have  been  mapped  on  Plate  III  (in  pocket) — the 
one,  a series  dominantly  basic  and  generally  of  dark  color  containing 
much  limestone,  biotite,  amphibolite,  and  graphite  schists  and 
termed  the  Packsaddle  schist,  a name  applied  originally  by  Com- 


o  Phillips,  W.  B.,  Tests  on  Texas  building  stones:  Mining  World,  June  24,  1905. 


GEOLOGY. 


15 


stock®  to  marbles  and  shaly  beds  near  Packsaddle  Mountain:  In  this 

report,  however,  the  name  is  redefined  and  limited  strictly  in  its 
usage  by  principles  to  be  presented  below.  The  other,  a series 
dominantly  acidic,  of  light  color,  containing  some  altered  limestone 
and  termed  the  Valley  Spring  gneiss,  a name  also  applied  by  Corn- 
stock6  and  also  redefined  in  this  report.  Bands  of  acidic  material  are 
found  in  the  first  series  and  bands  of  basic  dark  material  have  been 
included  in  the  second.  There  is  a transition  zone  between  the  two 
series,  locally  offering  difficulties  to  the  placing  of  definite  bounda- 
ries. Likewise,  within  the  acidic  series,  the  distinction  between 
invading  granites  and  gneisses  is  often  exceedingly  difficult  to  recog- 
nize, because  of  a gneissoid  texture  that  the  granites  locally  possess. 

The  distribution  of  the  two  series  is  dependent  primarily  on  major 
structural  relations,  modified  by  igneous  intrusion.  Their  general 
northwest-southeast  trend  is  determined  by  the  major  axes  of  fold- 
ing, and  the  lack  of  continuity  along  their  trends  is  due  to  the  pres- 
ence of  granite  (see  PI.  III).  Two  major  anticlinal  axes  are  present, 
one  passing  northwest  and  southeast  through  the  center  of  the  moun- 
tainous mass  just  west  of  Oxford,  the  other  passing  from  Packsaddle 
Mountain  northwest  to  a point  several  miles  west  of  Babyhead. 
Between  these  two  anticlinal  axes  a major  synclinal  axis  passes 
northwest  and  southeast  a short  distance  west  of  Llano.  The  broad 
band  determined  by  this  synclinal  axis  is  composed  largely  of  the 
Packsaddle  schist,  while  the  anticlinal  axes  mark  areas  of  the  lighter 
Valley  Spring  gneiss.  The  basic  Packsaddle  schist  overlies  the  acidic 
type,  and  therefore  is  found  on  the  eroded  flanks  of  these  great  folds, 
where  not  disturbed  by  granite  masses.  The  major  axes  of  folding 
do  not  represent  a simple  structure,  minor  folds,  some  of  which  have 
been  separately  mapped,  being  superimposed  upon  the  major  folds, 
with  the  result  that  local  complexities  of  structure  are  frequent.  No 
estimate  has  been  made  of  the  thickness  of  the  series. 

PACKSADDLE  SCHIST. 

DISTRIBUTION  AND  GENERAL  CHARACTER. 

The  Packsaddle  schist  series  includes  mica,  amphibole,  and  gra- 
phitic schists,  and  crystalline  limestone.  In  the  series  are  also  lighter- 
colored,  more  feldspathic  bands,  resembling  quartzites.  Intrusive 
rocks  of  earlier  age  than  the  granite,  of  the  diorite-gabbro  type,  are 
also  present  locally  in  considerable  amount.  They  have  been  sep- 
arated from  the  Packsaddle  schist  in  only  one  instance,  in  the  south- 
east corner  of  the  Llano  quadrangle  and  the  southwest  corner  of  the 
Burnet  quadrangle. 

a Comstock,  T:  B.,  Preliminary  report  on  the  geology  of  the  central  mineral  region  of  Texas:  First  Ann. 
Rept.  Texas  Geol.  Survey,  1889. 

b Loc.  cit. 


16  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

As  a whole,  the  Packsaddle  schist  is  characterized  by  an  excellent 
cleavage  which  for  the  most  part  accords  in  attitude  with  an  original 
bedding  in  sediments,  of  which  the  schists  represent  the  metamor- 
phosed equivalents.  Frequently,  though  not  invariably,  the  graphitic 
schists  are  closely  associated  with  limestones.  The  limestones  are 
developed  to  a varying  degree,  as  a glance  at  the  map  (PI.  Ill)  will 
show.  East  of  Oxford  numerous  limestone  beds  are  present,  and 
the  region  south  and  west  of  Llano  includes  many  bands.  In  general 
they  occur  wherever  the  Packsaddle  schist  is  found,  but,  though  most 
abundant  in  the  Packsaddle  schist  and  in  a measure  characteristic 
of  that  schist  series,  they  do  also  occur  in  the  lighter  series  (Valley 
Spring  gneiss),  though  usually  in  a still  more  altered  form;  that  is, 
as  wollastonite  bands.  The  graphitic  schists  carry  varying  propor- 
tions of  graphite — locally,  it  is  believed,  a sufficiently  high  content 
to  be  of  commercial  value.  (See  p.  77.)  A microscopic  examination 
of  a specimen  of  graphite  schist  from  Cottonwood  Creek  showed  about 
60  per  cent  of  quartz,  30  per  cent  of  orthoclase  feldspar,  fairly  abundant 
grains  of  augite,  a little  titanite,  a little  apatite,  and  flakes  of  graphite 
arranged  parallel  to  the  schistosity  of  the  rock.  Often  crystalline 
limestone  bands  are  interbedded  with  the  graphite  schist,  leaving 
little  or  no  doubt  as  to  the  sedimentary  origin  of  the  carbon  mineral. 
Among  the  remaining  types  of  a sedimentary  origin  are  mica,  tour- 
maline, and  quartz-feldspar  schists.  All  these  rocks  carry  a high 
content  of  quartz,  and  are  characterized  by  potash  feldspar  and  biotite 
with  here  and  there  some  pyroxene  (augite) . The  tourmaline  schist  is 
an  exception  and  does  not  carry  feldspar.  Magnetite,  titanite,  and 
apatite  are  often  accessories.  Amphibolite  schists  are  fairly  abun- 
dant and  are  characterized  by  a very  low  content  or  lack  of  quartz. 
There  is  some  doubt  regarding  their  origin.  As  they  are  interbedded 
with  limestones,  a sedimentary  origin  is  suggested;  their  origin  as 
old  flows  and  sill-like  intrusions,  however,  must  be  kept  in  mind,  as 
possible  or  even  probable,  for  basic  intrusive  rocks  are  found  in  the 
region,  and  in  one  place  a type  transitional  from  a basic  porphyry 
dike  to  amphibolite  schist  was  noted.  Amphibolites  of  undoubted 
igneous  origin  may  also  be  seen  in  considerable  masses. 

The  following  section  was  measured  on  the  west  fork  of  Oatman 
Creek,  about  3 } miles  south  of  Llano : 


Section  of  Packsaddle  schist  on  Oatman  Creek  east-southeast  of  Bachelor  Peak. 


Schist  with  pencil  cleavage 

Hidden 

Thin-bedded  feldspar-quartz  schist  (strike  N.  40°  W.,  dip  65°  E.). 

Well-banded  hornblende  schist 

Quartzite  (feldspar-quartz  schist) * . 

Hornblende  schist 

Thin-bedded  micaceous  schist 


Feet. 

1,000 

400 

3 

30 

1 

15 

75 


GEOLOGY. 


17 


Feet. 

More  massive,  micaceous  schist  with  pegmatite  and  quartz  injec- 


tions  130 

Graphitic  slate  schist *. 23 

Crystalline  limestone 24 

Graphitic  slate  schist 35 

Injection  gneiss 30 

Hornblende  schist 91 

Feldspar-quartz  schist 62  * 

Weathered  hornblende  schist 120 

Thin-bedded  mica  schist,  massive  as  a whole 60 

Limestone 8 

Graphitic  slate  or  schist 6 

Limestone 4 

Heavy,  thin-bedded  mica  schist  full  of  quartz  blebs  and  stringers.  32 

Friable  mica  schist  (like  p'encil  schist) 250 

Hidden 40 

Mica  schist 50 

Hidden 50 

Mica  schist 20 

To  granite  contact , 60 

2,  619 

PETROGRAPHY. 


The  results  of  a microscopic  examination  of  a number  of  specimens 
of  the  Packsaddle  schist  are  as  follows: 

Quartz-feldspar  schist. 

Megascopic  character. — A whitish-pink,  sugar-grained,  finely  banded  rock;  bands 
straight  and  narrow,  made  by  pink  and  white  constituents.  Speckled  with  magnetite 
showing  a slight  tendency  to  follow  bands.  Rock  cleavage  follows  bands. 

Microscopic  character. — Equidimensional  grains  microcline  feldspar,  orthoclase 
feldspar,  and  quartz.  Flakes  of  a brownish-yellow  biotite  mica  and  magnetite  not 
clearly  in  bands.  Considerable  alteration  of  feldspar.  Measurements  showed  68 
per  cent  feldspar,  32  per  cent  quartz — which  gives  76  per  cent  Si02,  approximately 
12  per  cent  A1203,  and  approximately  12  per  cent  K20. 

Quartzite-like  feldspar  schist. 

Megascopic  character. — Fine-grained,  almost  aphanitic,  grayish  and  pink  banded 
schist. 

Microscopic  character. — Event  granular,  fine-grained,  holocrystalline  rock,  two- 
thirds  orthoclase  feldspar  (altered),  one-third  quartz,  light-green  hornblende 
(partly  altered  to  chlorite),  and  titanite.  About  75  per  cent  Si02  and  12  per  cent 
A1203. 

Amphibolite  schist. 

Megascopic  character. — Dark-green  to  black,  finely-cleaved  schistose  rock. 

Microscopic  character. — Mass  of  hornblende  laths  in  a matrix  of  feldspar.  Abundant 
grains  titanite.  Little  calcite,  little  apatite. 

Amphibolite  schist. 

Megascopic  character. — Dense,  slaty,  almost  aphanitic,  dark-green  to  black  rock 
showing  on  weathered  surface  evidence  of  schistosity. 

Microscopic  character. — From  50  to  60  per  cent  light-green  hornblende,  considerable 
augite,  orthoclase,  and  some  plagioclase  feldspar  in  the  interstices  of  the  hornblende 

laths. 


74625°— Bull.  450—11 2 


18  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


Amphibolite  schist. 

Megascopic  character. — Dark-green  to  black  glittering  schist. 

Microscopic  character. — Linear  arrangement  of  abundant  dark-green  hornblende 
laths  in  a matrix  of  microcline  and  quartz,  the  former  in  great  excess.  Scattering 
grains  of  augite  partly  altering  to  hornblende.  Epidote,  magnetite,  apatite. 

Amphibolite  schist. 

m Megascopic  character. — Dark-green  to  black  very  fine  grained  glittering  schist. 

Microscopic  character. — Interlocking  grains  of  prismatic  light-green  hornblende 
evenly  though  not  entirely  equidimensional.  The  little  space  between  the  horn- 
blende plates  is  filled  with  feldspar. 

Biotite-quartz-mica  schist. 

Megascopic  character. — Gray  even  and  fine  grained  mica  schist. 

Microscopic  character. — Even,  granular  quartz,  orthoclase,  and  microcline.  Abun- 
dant biotite  laths  parallel  to  schistosity.  Some  muscovite. 

Mica  schist. 

Megascopic  character. — Gray  banded  schist.  Bands  due  to  lines  of  pink  feldspar  in 
light-gray  background.  Feldspar  is  arranged  in  lentils  which  produce  the  bands. 
Abundant  fine  flakes  of  black  mica. 

Microscopic  character. — About  equally  divided  quartz  and  altered  orthoclase  feld- 
spar. Abundant  biotite  in  linear  parallel  arrangement.  Abundant  iron  oxide  grains. 

Mica  schist. 

Megascopic  character. — Dark-greenish,  nearly  black  aphanitic  glassy  rock  showing 
on  surface  stria tions  which  reveal  its  schistose  nature. 

Microscopic  character. — Orthoclase  and  quartz  in  equidimensional  grains,  former  in 
slight  excess.  Biotite  mica  in  fine  parallel  alignment.  About  6 to  9 per  cent  mica. 

Quartz-tourmaline  schist. 

Megascopic  character. — Dense  dark-blue  to  black  hornfels-like  rock,  with  fine  bands 
of  quartz  showing  schistosity. 

Microscopic  character. — Fine  bands  of  quartz  and  tourmaline.  Tourmaline  for  the 
most  part  oriented  parallel  to  schistosity  and  apparently  crystallized  first,  as  it  appears 
in  fine  lines  in  the  quartz  parallel  to  bands.  Much  of  the  quartz  has  wavy  extinction. 

Biotite  feldspar  gneiss. 

Megascopic  character. — Blue-gray,  granular,  fine-grained  rock  with  gneissoid  aspect, 
rather  evenly  granular.  Mica  prominent  as  dark  constituent. 

Microscopic  character. — Granitoid  texture.  Quartz,  albite-oligoclase,  and  abundant 
biotite.  Some  hornblende,  titanite,  and  chlorite.  By  measurements  the  following 
approximate  chemical  composition  was  calculated:  73  per  cent  Si02,  14  per  cent 
A1203,  6 per  cent  Na20,  1 per  cent  CaO,  6 per  cent  Fe,  Mg,  etc. 

Mica  schist. 

Megascopic  character. — Pink  and  black  banded  schist,  with  finely  developed 
schistosity  due  to  mica. 

Microscopic  character. — Crystalline  granular  quartz.  Microcline  and  little  albite- 
oligoclase.  Biotite,  in  laths  or  plates  parallel  to  the  schistosity.  Quartz  arranged 
roughly  in  direction  of  schistosity.  Microcline  is  slightly  altered.  Composition:  79 
per  cent  silica,  9.64  per  cent  alumina,  8 per  cent  potash,  3.36  per  cent  iron,  magnetite, 
sodium,  and  calcium. 


GEOLOGY » 


19 


VALLEY  SPRING  GNEISS. 

DISTRIBUTION  AND  GENERAL  CHARACTER. 

The  mapping  of  the  Valley  Spring  gneiss  was  locally  attended  with 
many  difficulties,  partly  connected  with  separating  it  from  the  Pack- 
saddle  schist,  but  primarily  because  of  its  relation  to  granitic  intru- 
sions, which,  as  has  been  pointed  out,  are  widespread  and  of  all  degrees 
of  magnitude.  As  the  Valley  Spring  gneiss  often  closely  resembles  the 
granites,  especially  where  slight  schistosity  may  have  been  impressed 
upon  the  granites,  and  as  contacts  are  exceedingly  irregular  (a  feature 
characteristic  of  the  borders  of  large  intrusive  masses),  all  the  boun- 
daries shown  on  the  map  must  not  be  considered  as  definitely  sepa- 
rating distinct  formations,  but  rather  as  indicating  changes  in  the 
dominant  rock  type.  In  a region  where  intrusion  has  so  completely 
interleaved  and  at  places  actually  impregnated  a rock  mass,  and 
where  all  gradations  from  pure  granite  to  pure  schist  exist,  such 
boundaries  as  have  been  used  are  necessary  to  express  the  geologic 
facts.  In  many  places,  however,  the  boundaries  are  sharp  and  form 
definite  lines,  but  it  is  not  practicable  on  the  map  to  discriminate 
between  the  two  classes  of  boundaries.  It  is  believed,  also,  that  with 
the  schists  and  gneisses  of  sedimentary  origin  are  included  old  gneisses 
of  igneous  origin. 

Perhaps  the  most  distinctive  difference  between  the  light  Valley 
Spring  gneiss  and  the  dark  Packsaddle  schist  lies  in  their  difference 
of  massiveness.  This  difference  applies  more  particularly  when  the 
groups  are  taken  as  a whole  and  not  when  small  areas  are  compared. 
The  mountainous  tract  west,  southwest,  and  northwest  of  Oxford, 
including  Hobson  and  Blount  mountains,  and  the  area  south  and 
west  of  Babyhead,  and  including  Babyhead  Mountain,  contain  such 
massive  rocks,  typically  representing  the  Valley  Spring  gneiss.  A 
study  of  these  areas  leaves  the  impression  that  a thick  series  of 
sediments  of  rather  uniform  composition  has  been  involved  in  a zone 
of  intense  granitic  intrusion  and  metamorphism,  locally  in  a zone 
where  rock  flowage  and  minor  folding  have  been  dominant.  The 
dark  Packsaddle  schist  nowhere  presents  as  a whole  this  massive 
appearance. 

It  has  already  been  noted  that  dark  bands  occur,  though  not  abun- 
dantly, in  areas  mapped  as  Valley  Spring  gneiss,  and  also  bands 
composed  of  the  metamorphosed  equivalents  of  limestones — that  is, 
wollastonite.  These  bands  of  wollastonite  lend  plausibility  to  the 
hypothesis  that  metamorphism  has  been  most  intense  in  the  light 
series  (the  lower  series),  though  this  hypothesis  does  not  exclude  the 
generalization  that  intrusion  has  been  most  intense  along  synclinal 
axes,  as  the  position  of  the  great  granite  areas  indicates,  for  evidently 
wherever  the  dark  series  is  nearly  obliterated  by  areas  of  granite  the 
underlying  light  series  must  have  been  similarly  affected. 


20  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

PETROGRAPHY. 

The  results  of  a microscopic  examination  of  a number  of  specimens 
of  the  Valley  Spring  gneiss  are  given  below. 

Feldspar-quartz-mica  gneiss. 

Megascopic  character. — Finely  banded  sugar-grained  pink  and  black  gneiss.  Bands 
one-sixty-fourth  to  one-fourth  inch  in  width. 

Microscopic  character. — Potassic  feldspar,  more  or  less  altered,  and  quartz  about 
evenly  divided  with  feldspar.  Biotite  mica  (altered  to  chlorite  in  part)  in  linear 
arrangement.  Little  calcite.  Little  apatite. 

Feldspar-quartz  schist. 

Megascopic  character. — Nearly  white  aphanitic  schist.  Banding  due  to  quartz  bands 
separated  by  1-inch  to  |?-inch  aphanitic  bands. 

Microscopic  character. — Fine-grained,  granular  quartz  and  microcline,  the  former 
much  in  excess.  Feldspar  greatly  altered.  Little  muscovite. 

Quartz-feldspar  schist. 

Megascopic  character. — Pink,  fine  sugar-grained  rock  with  only  slight  schistosity  in 
hand  specimen.  Flecked  with  small  grains  of  magnetite  evenly  distributed. 

Microscopic  character. — Altered  microcline  feldspar  dominant.  Little  albite- 
oligoclase.  Quartz  abundant,  though  less  than  feldspar.  Few  flakes  of  biotite. 
Magnetite  scattered. 

Quartz-feldspar  schist. 

Megascopic  character. — Even- toned  pink  fine-grained  rock.  Banding  brought  out 
by  quartz  and  feldspar,  arranged  in  lines.  Fine  dust  of  magnetite,  little  muscovite, 
and  little  garnet. 

Microscopic  character . — Holocrystalline  grains  quartz,  potash  feldspar,  mostly  micro- 
cline, and  abundant  muscovite.  Approximate  composition:  68.6  per  cent  silica,  16 
per  cent  alumina,  11  per  cent  potash,  1.48  per  cent  calcium,  2 per  cent  magnetite. 

ORIGIN  OF  THE  SCHISTS  AND  GNEISSES. 

The  schists  described  above,  those  of  both  the  light  and  the  dark 
series,  are  all  completely  crystallized;  that  is,  the  arrangement,  the 
size,  and  the  composition  of  their  mineral  constituents  are  due  in 
part  to  the  influence  of  heat  and  pressure  and  in  part  to  flowage  as 
a mass.  The  presence  of  crystalline  limestones  and  of  graphite  and 
mica  schists,  traceable  for  long  distaiices  and  retaining  the  charac- 
teristics of  beds,  leaves  no  room  for  doubt  that  these  rocks  were 
in  great  part  formed  by  metamorphism  from  a sedimentary  series. 
It  is  believed  also  that  the  presence  of  iron  ores  leads  to  the  same 
conclusion — a point  which  will  be  more  fully  considered  at  another 
place.  As  has  been  pointed  out,  the  amphibolites,  because  of  their 
basic  character,  probably  represent  in  part  old  basic  intrusives  or 
flows,  or  perhaps  sediments  of  a tuffaceous  nature. 

Gneisses  derived  by  metamorphism  from  intrusive  rocks  of  a 
granitic  type  are  almost  without  doubt  present  in  the  region.  One 
crosscutting  dike  possesses  much  the  same  schistose  nature  as  the 


GEOLOGY. 


21 


beds  which  it  cuts.  Red  Mountain  also,  a granitic  ridge  in  the  south- 
east corner  of  the  Llano  quadrangle,  is  a noteworthy  example  of  the 
same  phenomenon.  This  ridge  trends  northwest,  and  the  dike 
which  forms  it  can  be  traced  to  a point  near  Walker  Peak.  Toward 
the  northwest  a gradual  change  takes  place  in  the  appearance  of  the 
mass,  and  the  rock  at  its  northwest  end  shows  decided  lamination. 
Indeed,  were  the  rock  exposed  only  in  the  condition  seen  at  this  end, 
it  could  not  be  distinguished  from  beds  which  are  believed  to  repre- 
sent sedimentary  strata. 

In  the  area  immediately  east  of  Long  Mountain  also  the  gneissoid 
rocks  have  much  the  aspect  of  granites  impressed  with  foliate  struc- 
ture; and  south  of  Field  Creek,  near  San  Fernando  Creek,  in  the 
northwest  part  of  the  quadrangle,  similar  features  were  noted.  It 
should  be  understood,  then,  that  the  series  of  gneisses  and  schists  of 
the  acidic  type  mapped  as  Valley  Spring  gneiss  probably  contains 
material  of  igneous  origin.  It  may  be  said  here  that  no  genetic 
relation  could  be  shown  between  the  iron-ore  deposits  and  these  old 
granitic  intrusive  rocks. 

BASIC  INTRUSIVE  ROCKS  OF  A GABBRO-DIORITE  TYPE. 

GENERAL  CHARACTER  AND  DISTRIBUTION. 

The  dark  intrusive  rocks  are  most  abundantly  developed  in  the 
southeast  corner  of  the  Llano  quadrangle,  and,  though  they  have 
not  been  generally  separated  from  the  accompanying  dark  Packsaddle 
schist,  they  have  been  mapped  in  one  instance.  A considerable 
mass  of  gabbro  was  observed  in  the  vicinity  of  Goldmine  Creek, 
north  of  Moss  ranch,  but  it  has  not  been  mapped;  and,  as  has  been 
stated,  the  dark  Packsaddle  schist  probably  includes  amphibolites, 
which  represent  old  intrusive  rocks  of  gabbroic  or  diabasic  type. 

The  area  south  of  Click  is  especially  characterized  by  very  dark 
green  to  black  amphibolite  rocks,  which  were  probably  derivatives 
of  a gabbro  or  diorite  magma.  The  talc  deposits  in  this  vicinity  are 
alteration  products  of  such  a series,  and  the  serpentine  rocks  of 
Oxford  are  probably  derived  from  a peridotitic  magma. 

Two  dark  fine-grained  dikes  (aphanitic  in  texture)  which  cut  the 
schist  series  and  which  might  have  been  expected  to  show  a rather 
basic  character  proved  to  be  felsites,  one  a spherulitic  mica  felsite, 
the  other  a hornblende-mica  felsite;  the  hornblende  of  this  latter 
rock  showed  a bluish  pleochroism  parallel  to  the  C axis,  suggestive 
of  a soda  amphibole.  A short  distance  east  of  Click  a small  intru- 
sive mass  proves  to  be  a hornblende-soda  granite. 

The  rocks  of  this  gabbro-diorite  group  were  intruded  earlier  than 
the  greater  part  of  the  granites.  It  is  possible  that  some  of  the  latter 
rocks,  which  show  evidence  of  pressure  and  metamorphism,  may 
have  been  nearly  of  the  same  age,  though  no  relations  were  observed 
which  might  establish  this  point. 


22  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


PETROGRAPHY. 

The  results  of  a microscopic  examination  of  a number  of  specimens 
are  as  follows: 

Soda-hornblende  granite,  chip  only,  taken  a short  distance  east  of  Click  post  office. 

Microscopic  character. — Holocrystalline  albite  feldspar  and  considerable  quartz;  a 
little  microcline  feldspar.  Large  plates  of  green  hornblende  are  abundant.  Abun- 
dant titanite  surrounding  grains  of  titaniferous  magnetite.  The  rock  has  suffered 
crushing  and  shows  abundant  granulation  at  the  edges  of  the  feldspar  grains;  the 
amphiboles  are  locally  broken  and  bent  and  drawn  into  shreds. 

Hypersthene  olivine  gdbbro  from  Goldmine  Creek. 

Megascopic  character. — Dark-blue  to  black  medium-grained  rock. 

Microscopic  character. — Holocrystalline  texture.  Labradorite  in  lathlike  prisms. 
Diallage,  hypersthene,  and  olivine.  Biotite  and  hornblende  poikilitically  inclosing 
pyroxene  and  feldspar.  Magnetite. 

Amphibolite  from  high  hill  on  Coal  Creek. 

Megascopic  character. — Dark -green  hornblende  rock  with  slight  tendency,  due  to 
pressure,  to  cleave  more  easily  in  one  direction  than  in  another. 

Microscopic  character. — Mat  of  light-green  hornblende  with  plagioclase  feldspar  in 
interstices.  Shows  evidence  of  crushing. 

Metadiorite  porphyry  in  hornblende  schist  series  near  Aaron  Moss  ranch. 

Microscopic  character. — Altered  andesine-labradorite  feldspar  phenocrysts  in  a fine- 
grained groundmass  of  feldspar  and  green  hornblende.  Flo  wage  of  hornblende 
around  the  phenocrysts  of  feldspar  noteworthy.  Shows  an  intermediate  stage  in  the 
formation  of  an  amphibole  schist. 

Dioriie  from  Cedar  Mountain  under  Cambrian. 

Megascopic  character. — Medium-grained  dark  gray  to  green  rock. 

Microscopic  character. — Holocrystalline  andesine-labradorite  and  hornblende  in 
large  plates. 

Spherulitic  mica  felsite. 

Megascopic  character.— Black  aphanitic  dike  rock. 

Microscopic  character. — Mass  of  very  fine  blades  of  biotite  mica  in  groundmass  of 
unstriated  feldspar.  Some  quartz  and  one  quartz  phenocryst,  showing  absorbed 
edges.  A spherulitic  arrangement  of  the  feldspar  is  noteworthy  and  the  mica 
seems  to  be  arranged  in  a manner  controlled  perhaps  by  this  spherulitic  structure. 

Amphibolite  ( meta-gabbro ?)  ( partly  crushed)  from  southwest  part  of  Burnet  area  near 

edge  of  Llano  area. 

Megascopic  character. — Dark-green  medium  to  fine-grained  hornblende  rock. 

Microscopic  character. — Mass  of  interlocking  hornblende  crystals  with  interstices 
filled  with  untwinned  plagioclase  feldspar.  Abundant  grains  of  magnetite  largely 
within  the  hornblende. 

Mica-hornblende  felsite. 

Megascopic  character. — Nearly  black  aphanitic  dike  rock. 

Microscopic  character. — Abundant  hornblende  in  laths  and  grains  set  in  a matrix  of 
very  finely  granular  feldspar  and  quartz.  Biotite  mica  is  also  abundant  in  fine  laths 
and  tiny  plates.  Apatite  needles  are  present.  The  hornblende  has  a blue  pleo- 
chroism  parallel  to  the  elongation  (C),  and  extinction  angles  as  high  as  18°. 


GEOLOGY. 


23 


Diorite  from  southeast  of  Rough  Mountain  and  west  of  San  Fernando  Creek. 

Megascopic  character. — Medium-grained  dark-green  rock. 

Microscopic  character. — Holocrystalline  texture.  Weathered  andesine-labradorite 
feldspar  and  abundant  hornblende  in  large  plates.  Much  pyrite  in  large  part  confined 
to  hornblende.  Hornblende  altering  to  iron  oxide  along  cleavage  cracks.  Some 
epidote.  Some  apatite. 

PALEOZOIC  ROCKS. 

The  Paleozoic  formations  in  the  Llano-Burnet  region,  as  stated  in 
an  earlier  portion  of  this  report,  surround  a basin  cut  in  pre-Cambrian 
rocks,  and  much  of  the  section  therefore  is  exposed  about  the  edges 
of  this  relatively  low-lying  area. 

The  pre-Cambrian  rocks,  composed  in  large  part  of  metamorphosed 
marine  sedimentary  beds,  passed  through  all  the  stages  of  deposition, 
deep  burial,  folding,  metamarpliism,  intrusion,  elevation,  erosion,  and 
subsidence  beneath  the  sea  before  the  basal  Paleozoic  beds  were 
deposited.  It  is  evident,  therefore,  that  a vast  interval  of  time 
separates  the  periods  during  which  the  two  series  were  formed.  This 
time  interval  is  expressed  by  the  unconformity  between  the  Paleo- 
zoic beds  and  the  underlying  schists  and  granites.  As  this  report 
treats  principally  of  the  pre-Cambrian  rocks  and  the  relations  of  the 
economic  resources  thereto,  the  Paleozoic  rocks  will  be  very  briefly 
discussed. 

UPPER  CAMBRIAN  ROCKS. 

The  Upper  Cambrian  rocks  of  this  area  are  believed  to  be  essen- 
tially the  equivalent  of  the  Reagan  sandstone  in  Oklahoma.  They 
rest  upon  a pre-Cambrian  complex  of  metamorphic  rocks — the  schists, 
gneisses,  and  intrusive  rocks  described  above — and  have  been 
divided  into  three  formations,  namely,  proceeding  from  the  base 
upward,  the  Hickory  sandstone,  the  Cap  Mountain  formation,  and 
the  Wilberns  formation.® 

A variable  thickness  of  conglomerate  and  sandstone,  up  to  250 
feet,  comprises  the  lower  formation  to  which  the  name  Hickory  sand- 
stone is  given,  a name  originally  applied  by  Comstock  b to  sandstones 
in  the  valley  of  Hickory  Creek  and  its  tributaries.  Next,  but  with 
a gradual  transition  from  sandstone  to  limestone,  are  beds  predomi- 
nantly limestone,  capped  by  a variable  thickness  (from  15  to  75  feet) 
of  cross-bedded  glauconitic  sandstone;  these  strata,  90  feet  thick, 
constitute  the  second  formation,  the  Cap  Mountain,  which  is  typi- 
cally exposed  at  Cap  Mountain,  in  the  Llano  quadrangle.  The  third 
formation,  the  Wilberns,  from  170  to  220  feet  thick,  includes  lime- 
stones and  shales,  the  shales  occupying  approximately  the  upper 
third  of  the  formation.  It  is  typically  exposed  near  Wilberns 
Glen,  in  the  Llano  quadrangle. 

a For  detailed  descriptions  of  these  formations  see  Llano-Burnet  folio,  Geol.  Atlas  U.  S.,  U.  S.  Geol. 
Survey.  (In  preparation.) 

b Comstock,  T.  B.,  Preliminary  report  on  the  geoiogy  of  the  central  mineral  region  of  Texas:  First  Ann. 
Kept.  Texas  Geol.  Survey,  1889. 


24  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

CAMBRO-ORDOYICIAN  ROCKS. 

The  Cambro-Ordovician  rocks  have  not  been  subdivided.  They 
are  represented  by  the  Ellenburger  limestone  (locally  dolomitic).a 
There  is  believed  to  be  an  unconformity  near  the  top  of  the  formation, 
for,  according  to  XJlrich,  fossil  evidence  precludes  the  idea  that  con- 
tinuous sedimentation  could  have  been  in  progress  during  the  deposi- 
tion of  the  entire  series  of  beds.  The  formation  is  composed  of 
chert-bearing  limestones  and  dolomites,  which  are  typically  exposed 
in  the  Ellenburger  Hills,  in  the  Burnet  quadrangle.  In  the  greater 
number  of  places  where  the  base  of  these  beds  was  observed,  apparent 
conformity  with  the  Wilberns  formation  existed,  though  in  several 
places  on  Riley  Mountain  an  angular  limestone  conglomerate  was 
present.  Here,  also,  some  evidence  of  overlap  was  observed,  but 
the  writer,  in  view  of  the  fa'ct  that  faulting  was  found  to  be  preva- 
lent, wishes  to  leave  this  point  open  until  opportunity  may  be  offered 
to  study  the  locality  again.  In  the  majority  of  places,  however, 
where  the  conglomerate  was  noted,  concordance  of  beds  was  the 
rule.  Many  observations  were  made  where  no  unconformity  could 
be  detected,  and  also  where  apparent  transition  of  the  two  forma- 
tions could  be  followed.  It  must  be  noted,  however,  that  the  basal 
beds  of  the  Ellenburger  limestone  varied  in  texture  and  appearance; 
and  as  this  phenomenon  is  in  itself  a suggestion  of  unconformity, 
any  conclusion  must  for  the  present  remain  tentative. 

At  the  top  of  the  Ellenburger  limestone  a conglomeratic  limestone 
bed  is  generally,  though  not  always,  present,  and  the  lowest  portion 
of  the  upper  Carboniferous  succeeds.  The  deposition  of  upper  Car- 
boniferous limestone  on  beds  of  Cambro-Ordovician  age  marks  a 
great  gap  in  sedimentation,  a period  of  great  duration  including 
lower  Carboniferous,  Devonian,  Silurian,  and  part  of  Ordovician 
time,  during  which  no  deposition  was  taking  place. 

The  Cambro-Ordovician  rocks  occur  at  the  crest  of  the  Paleozoic 
scarp  (unless  faulting  has  intervened)  and  form  the  greater  part  of 
the  Paleozoic  surface  in  Llano  and  Burnet  Counties. 

Complete  sections  of  the  Ellenburger  limestone  are  not  easy  to 
obtain.  The  general  massiveness  of  the  formation,  gentle  folds  and 
faults,  combine  to  prevent  continuous  record.  Thicknesses  up  to  600 
feet  may  be  observed  in  the  bluffs  of  the  Colorado,  between  Tanyard 
Crossing  and  Deer  Creek,  and  it  is  probable  that  the  formation  is 
composed  of  beds  aggregating  1,000  feet  in  thickness. 


CARBONIFEROUS  ROCKS. 

Beds  of  Carboniferous  limestone  and  shale  of  lower  Pennsylvanian 
age  are  present  in  this  region  and  have  been  divided  into  two  forma- 
tions— the  Marble  Falls  limestone,  composed  of  limestone,  and  the 


a For  detailed  description  of  the  formation  see  Sidney  Paige,  Llano-Burnet  folio,  Geol.  Atlas  U.  S., 
U.  S.  Geol.  Survey.  (In  preparation.) 


GEOLOGY. 


25 


Smith  wick  shale, a composed  of  nearly  black  shale  accompanied  by 
sandstone  lentils. 

As  has  been  already  noted  the  Carboniferous  is  in  most  places 
separated  from  the  underlying  Cambro-Ordovician  by  a thin  lime- 
stone conglomerate,  and,  in  one  instance,  a very  coarse,  angular 
conglomerate  or  breccia  was  observed.  In  some  localities,  however, 
little  or  no  discordance  could  be  seen,  as  in  the  restricted  basin  5 miles 
northeast  of  Blufton  in  the  Burnet  quadrangle. 

The  Marble  Falls  limestone  is  believed  to  be  not  over  450  feet, 
possibly  500  feet,  in  thickness.  The  Smithwick  shale,  which  imme- 
diately overlies  the  Marble  Falls  limestone,  because  of  its  soft  nature 
is  not  exposed  in  such  attitude  as  to  permit  a section  measurement. 
Moreover,  its  top  is  overlapped  by  Cretaceous  sediments.  Probably 
the  beds  exposed  in  Burnet  County  do  not  exceed  400  feet  in  thickness. 

The  Carboniferous  is  confined  almost  entirely  to  the  southeastern 
portion  of  the  Burnet  quadrangle,  though  a small  area  exists  in  Riley 
Mountain. 

STRUCTURE. 

A reference  to  the  small  map  of  Texas  (PI.  I,  p.  7),  showing  the 
geologic  relations  of  the  Llano-Burnet  region  and  surrounding  area, 
will  immediately  call  forth  the  suggestion  that  some  unusual  con- 
dition has  caused  the  exposure  of  these  ancient  pre-Cambrian  rocks* 
and  on  turning  to  the  detailed  map  (PL  III,  in  pocket)  and  studying 
the  faulting  which  has  taken  place,  one  is  compelled  to  ascribe  to  this 
faulting,  combined  with  differential  erosion,  the  present  basin-like 
form  of  the  area. 

The  faults  which  border  this  basin,  indicated  by  heavy  black  lines, 
all  have  one  important  similarity.  The  downthrown  block  forms  the 
scarp  side  of  the  fault  and  presents  a more  or  less  vertical  face  toward 
the  basin,  or,  in  other  words,  the  basin  area,  now  topographically 
lower  than  the  surrounding  scarp  arid  largely  characterized  by  pre- 
Cambrian  rocks,  is  structurally  elevated  with  respect  to  that  scarp. 

Such  an  elevation  in  past  time  must  have  exposed  the  rocks  which 
were  carried  up  by  it  to  accelerated  attack  by  the  elements  with  the 
result  that  the  overlying  sediments  were  stripped  off  and  the  core  of 
schists  and  granite  uncovered.  From  this  point  on,  the  metamorphic 
complex  disintegrated  more  rapidly  than  the  surrounding  linestone- 
capped  strata,  and  the  present  erosional  basin  was  formed.  The 
Paleozoic  sediments  involved  in  the  suggested  uplift  are  locally  folded, 
and  are  inclined  at  varying  degrees  from  the  horizontal. 

The  structure  of  the  pre-Cambrian  schists  (except  the  displacement 
they  have  suffered  due  to  late  faulting)  is  of  a much  earlier  date  and 
of  a much  more  complex  nature  than  the  structures  just  described. 


a For  detailed  descriptions  of  the  Smithwick  shale  see  Llano-Burnet  folio,  Geol.  Atlas  U.  S.,  IT.  S. 
Geol.  Survey.  (In  preparation.) 


26  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

The  rocks  have  suffered  deep-seated  regional  metamorphism,  have 
been  impressed  with  a foliate  structure,  have  usually  steeply  inclined 
dips,  trend  generally  to  the  northwest,  and  are  intruded  both  by  old 
dioritic  and  gabbroic  rocks  and  by  late  granitic  and  pegmatitic  types. 
The  major  structural  lines  are  indicated  on  the  geologic  map  (PI.  III). 
Two  nearly  parallel  anticlinal  axes  are  specially  noteworthy,  one  a 
few  miles  west  of  Oxford,  the  other,  a few  miles  east  of  Lone  Grove. 
The  latter  ends  to  the  southeast  in  the  Burnet  quadrangle  (not  shown 
here),  and  is  beautifully  accentuated  by  heavy  bands  of  limestone, 
bending  around  the  nose  of  the  arch. 

Several  of  the  many  minor  folds  are  indicated  on  the  map.  The 
great  granite  masses  occupy  positions  corresponding  to  synclinal  axes, 
as,  for  example,  the  mass  in  the  southwestern  part  of  Llano  quadrangle, 
and  the  mass  in  the  western  part  of  Burnet  quadrangle.  The  central 
syncline  does  not  seem  to  have  suffered  such  intense  intrusion. 

North  of  Llano  River  in  the  western  portion  of  the  Llano  quad- 
rangle the  anticlinal  arch  flattens  and  the  schists  dip  at  lower  angles. 

The  manner  in  which  intrusion  has  taken  place  has  already  been 
described  and  need  not  be  repeated.  A study  of  the  map  will  indi- 
cate, in  part,  the  extreme  point  to  which  this  process  has  been  carried. 
A discussion  of  the  probable  forces  involved  in  the  production  of  the 
post-Paleozoic  faulting  can  not  be  given  in  this  paper. 

IRON  ORES.  « 

GENERAL  DESCRIPTION. 

By  A.  C.  Spencer. 

• 

Iron  ores  composed  essentially  of  magnetic  iron  oxide  (magnetite) 
(Fe304)  or  of  admixtures  of  magnetite  with  hematite  (Fe203)  occur 
in  deposits  of  noteworthy  size  in  Llano  and  Mason  Counties,  Tex. 
During  the  progress  of  geologic  mapping  of  the  Llano  quadrangle  in 
1908  and  1909  thirty- two  more  or  less  distinct  occurrences  of  such 
iron  ore  were  noted  and  studied  with  such  detail  as  was  warranted  by 
generally  poor  natural  exposures  and  a very  small  amount  of  explo- 
ratory development. 

Though  a few  localities  are  in  eastern  Mason  County,  most  of  the 
iron  showings  are  in  that  portion  of  Llano  County  which  lies  north 
of  Llano  River.  All  of  the  known  occurrences  of  magnetite  are 
described,  but  it  is  believed  that  not  more  than  perhaps  three  of  the 
deposits  promise  to  become  of  industrial  value.  No  assurance  can  be 
given  that  the  three  most  likely  deposits  can  be  developed  into  profit- 


a The  examination  of  the  iron-ore  deposits  was  assumed  as  an  especial  task  by  Mr.  Spencer  in  view  of  his 
familiarity  with  the  magnetite  ores  of  the  northeastern  portion  of  the  United  States,  but  the  more  notable 
showings  were  also  studied  by  Mr.  Paige.  The  notes  of  both  have  been  used 'in  the  following  descriptions. 


IRON  ORES. 


27 


able  mines  in  advance  of  adequate  exploration  by  means  of  diamond 
drills  or  by  prospecting  'shafts  in  addition  to  those  already  opened, 
and  it  is  considered  that  the  less  promising  deposits  will  not  war- 
rant any  large  expenditure  for  prospecting  unless  the  market  value 
of  iron  ores  increases. 

The  permissible  scope  of  the  geologic  work  did  not  admit  of  mag- 
netic surveys,  but  it  is  suggested  that  such  surveys  should  be  carried 
on  in  connection  with  any  future  exploration  of  the  more  promising 
magnetic  deposits  of  this  district.  Surveys  with  compass  and  dip 
needle  would  perhaps  serve  as  adequate  guides  in  the  preliminary 
magnetic  exploration  of  these  iron-ore  deposits,  after  which,  if  the 
results  obtained  warranted  such  a course,  more  refined  methods  and 
studies  might  be  applied. 

Financial  interests  that  may  take  up  the  problem  of  the  practical 
development  of  the  Llano  County  iron  ores  will  doubtless  give  due 
consideration  to  the  possibility  of  applying  magnetic  concentration, 
as  processes  of  this  sort  are  becoming  more  and  more  firmly  estab- 
lished in  various  parts  of  the  world. 

The  deposits  of  magnetite  in  Llano  and  Mason  counties,  Tex., 
are  typically  layered  or  stratiform  ore  bodies  conforming  in  attitude 
with  the  layering  of  the  somewhat  schistose  rocks  by  which  they  are 
inclosed.  The  feature  of  layering  is  more  marked  in  the  leaner  ore 
bodies  than  in  the  deposits  of  higher  grade,  but  may  be  made  out  in 
nearly  every  locality  where  the  ore-bearing  rocks  are  adequately 
exposed  for  any  sort  of  an  examination.  A single  exception  is  noted 
in  the  case  of  a small  ore  mass  opened  by  the  Gallihaw  shaft,  which 
occurs  in  a dike  cutting  across  the  layering  of  the  local  gneiss. 

In  so  far  as  the  geologic  mapping  may  be  relied  on  the  deposits  are 
associated  mainly  with  the  lower  of  the  two  sets  of  gneisses  which 
have  been  broadly  separated.  The  difficulties  of  consistently  dis- 
criminating between  these  rocks  have,  however,  proved  to  be  so  great 
that  it  must  be  freely  admitted  that  the  immediate  country  rocks  of 
the  ores  may  be  representatives  of  the  upper  set  of  schists  in  certain 
localities.  If  any  mistake  has  been  made  in  the  proper  classification 
of  the  country  rocks,  it  is  in  places  where  the  upper  schists  have  suf- 
fered excessive  metamorphism  and  where  they  constitute  areas  of 
minor  extent. 

Two  extensive  occurrences  of  magnetite  were  found  within  areas 
which  are  undoubtedly  underlain  by  the  upper  dark  schists,  the 
Packsaddle  schist,  and  a small  amount  of  magnetite  was  noted  at  ^ 
one  other  place  in  this  rock.  The  Olive  deposit,  which  is  included  in 
the  foregoing,  occurs  in  the  dark  Packsaddle  schist  near  beds  of  lime- 
stone and  very  near  the  edge  of  a great  intrusion  of  coarse  granite. 


28  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

SPECIAL  LOCALITIES. 

OLIVE  PROPERTY. 

By  A.  C.  Spencer. 

The  Olive  iron-ore  property  is  located  on  Little  Llano  River  about 
6 miles  east  by  northeast  of  Llano,  1 mile  south  of  Lone  Grove  post 
office,  and  1 mile  north  of  Llano  River  and  the  line  of  the  Houston 
& Texas  Central  Railroad.  The  property  has  been  more  exten- 
sively developed  than  any  other  in  the  district.  It  was  opened  by  a 
shaft  in  1892  or  1893. 

An  extensive  area  of  granite  covering  the  western-central  part  of 
the  Burnet  quadrangle  and  the  adjacent  portion  of  the  Llano  quad- 
rangle is  bounded  on  the  southwest  and  west  by  a band  of  limestone- 
bearing schists  extending  along  the  railroad  southeast  and  northwest 
from  Graphite  station  and  up  the  valley  of  Little  Llano  River.  The 
Olive  shaft  is  situated  on  the  east  bank  of  the  Little  Llano  just  west 
of  the  main  boundary  between  the  schists  and  granites,  and  therefore 
within  the  schists  which  belong  to  the  upper  set  of  metamorphosed 
sedimentary  rocks  characteristic  of  the  region. 

The  rocks  exposed  in  the  vicinity  include  granite,  hornblende-mica 
schist,  graphite  schist,  and  crystalline  limestone.  The  granites  are 
intruded  into  the  other  rocks  in  an  intricate  manner  which  can  not 
be  fully  made  out  because  of  rather  poor  exposures,  so  that  the  repre- 
sentation of  areal  relations  given  on  the  geologic  map  is  of  necessity 
very  much  generalized.  The  material  on  the  waste  dump  includes 
all  the  rocks  mentioned  except  graphite  schist. 

The  stock  pile  contains  perhaps  400  tons  of  ore  of  very  good  phys- 
ical appearance.  Most  of  the  ore  contains  hornblende,  and  some  of 
it  carries  iron  sulphide  in  addition  to  magnetite.  It  is  all  more  or 
less  distinctly  layered  in  its  make  up.  As  the  result  of  17  years’ 
exposure  many  of  the  ore  chunks  present  a somewhat  weathered 
appearance,  the  partial  disintegration  being  due  to  oxidation  of  the 
iron  sulphide  present.  Where  this  mineral  is  lacking,  the  ore  shows 
no  effects  of  weathering. 

The  following  analyses  show  the  character  of  the  ore: 

Analyses  of  iron  ore  from  Olive  mine , Llano  County , Tex. 


Metallic 

iron. 

Silica. 

Sulphur. 

Phos- 

phorus. 

1 

57. 80 

8. 40 

0.28 

Trace. 

2 

54. 35 

10.16 

.55 

.021 

3 

57.5 

8.6 

Trace. 

Trace. 

1 and  2 are  samples  taken  by  Robert  Linton,  of  Atwater,  Linton  & Atwater,  mining  engineers,  for 
Johnston,  Elliot  & Co.,  of  Dallas,  Tex. 

3.  S .H.  Worrell,  analyst,  University  of  Texas. 


IRON  ORES. 


29 


Mr.  Robert  Linton  has  furnished  also  the  following  analyses,  said 
to  have  been  made  in  1893  for  the  owners  of  the  Olive  property. 
Though  the  name  of  the  analyst  is  not  given,  there  is  no  reason  to 
believe  that  these  are  not  good  commercial  analyses.  The  samples 
taken  together  are  stated  to  have  come  from  the  third  mine  level  and 
to  represent  a section  across  9 feet  6 inches  of  ore,  9 feet  2 inches  of 
which  is  covered  by  samples  5 to  11  in  the  following  table.  These 
samples  show  an  average  content  of  iron  of  58.71  per  cent  and  of 
phosphorus  of  0.0325  per  cent,  this  average  being  figured  with  due 
consideration  of  the  widths  of  ore  stated  in  the  table. 

The  analyses  show  a strictly  Bessemer  type  of  ore  with  a moderate 
iron  content.  Sulphur,  though  rather  high,  is  not  sufficient  to  lower 
the  value  of  the  ore  appreciably. 

Analyses  of  iron  ore  from  third  mine  level , Olive  mine,  Llano  County,  Tex. 


Analysis 

No. 

Width 
of  ore. 

Fe203. 

Fe. 

P. 

S. 

Si02. 

Mn. 

Ti02. 

Ft.  in. 

5 

2 

91. 76 

64. 33 

0. 0264 

0. 58 

81.52 

6 

1 

87. 17 

61.02 

.0177 

.93 

11.08 

2. 25 

7 

2 

24.08 

.0607 

2.21 

25.28 

8 

2 3 

89.27 

62. 49 

.0104 

.32 

8. 87 

9 

2 

69. 81 

48. 87 

.0279 

.64 

19.43 

10 

10 

60. 50 

42. 35 

.0569 

.53 

22.  41 

11 

1 2 

61.06 

42.  74 

.0663 

.47 

25. 14 

12 

- 8 

88.34 

61.84 

.0168 

.64 

10. 54 

1 

Total. 


100. 51 
101.  44 


98. 47 
89.90 
83.49 
86.73 
99.53 


The  Olive  ore  was  discovered  at  a point  about  95  feet  north  by 
northeast  of  the  working  shaft.  There  is  no  surface  showing  and  the 
ore  is  said  to  have  been  uncovered  by  accident  in  a shallow  excava- 
tion. The  first  development  was  by  means  of  an  incline  about  30 
feet  deep  and  of  a southerly  drift,  which  was  afterwards  connected 
with  the  vertical  working  shaft.  The  latter,  which  was  started  in  the 
hanging  wall,  encountered  the  ore  below  the  level  of  the  drift  men- 
tioned above.  It  was  carried  down  through  and  below  the  ore,  and 
three  crosscuts  were  run  out  to  the  ore. 

The  following  notes  by  J.  B.  Dabney,  former  superintendent  of 
the  Olive  mine,  are  furnished  by  Mr.  N.  J.  Badu,  of  Llano: 

The  vein  lies  northeast  and  southwest.  The  ore  was  good  on  the  first  heading,  but 
not  so  good  as  on  the  second,  third,  and  fourth  levels.  On  the  fourth  level  the  ore 
pinched  to  2 feet.  The  heading  on  this  level  was  carried  20  feet  beyond  the  vein  and 
then  abandoned.  Next  an  incline  was  driven  to  the  vein  which,  as  near  as  I can 
remember,  was  8 feet  wide.  From  the  bottom  of  the  incline  the  vein  was  opened  to 
right  and  left. 

The  cross  section  of  the  mine  given  herewith  (fig.  2)  is  adapted  from 
a sketch  by  Mr.  Dabney  on  the  sheet  bearing  the  notes  already  given. 
On  his  sketch  he  notes  the  thickness  of  the  vein  above  the  first  level 
as  3 feet;  between  the  first  and  second  levels,  6 feet;  between  the 


30  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


third  and  fourth  levels,  8 feet;  at  the  fourth  level,  2 feet;  and  at  the 
bottom  of  the  incline,  8 feet. 

For  the  sketch  plan  of  the  mine  workings  here  given  the  writer  is 
indebted  to  Mr.  Robert  Linton,  who  secured  it  from  mine  records 
which  passed  through  his  hands  during  the  summer  of  1909. 

From  the  data 

Looking  north  , i i •,  i 

at  hand  it  may  be 
concluded  that  the 
Olive  ore  body 
strikes  approxi- 
mately northeast 
and  southwest  and 
dips  rather  steeply 
toward  the  north- 
west and  beneath 
Little  Llano  River. 
The  relative  posi- 
tions of  the  mine 
levels  and  the  apex 
of  the  vein  at  the 
discovery  s h af  t 
suggest  that  the 
ore  body  may  be  a 
pod-shaped  mass, 
plunging  in  a 
southerly  direc- 
tion, but  it  is  not 
known  that  any 
horizontal  limit  of 
the  ore  was  estab- 
lished at  any  point. 

Observable  rela- 
tions at  the  Olive 
mine  do  not  lead 
to  any  conclusion 
concerning  the 
mode  of  origin  to 
be  assigned  to  the 
deposit.  Lying  at 
the  edge  of  a great 
granite  intrusion,  the  ore  might  have  been  segregated  as  an  effect 
of  igneous  metamorphism.  However,  the  material  on  the  waste 
dump  can  not  be  regarded  as  in  any  way  particularly  character- 
istic of  intense  igneous  metamorphism,  the  limestone  and  schist 
being  quite  like  the  general  run  of  the  rocks  which  compose  the 
upper  of  the  two  sets  of  schist  (Packsaddle  schist)  which  have 


IRON  ORES. 


31 


been  delineated  on  the  geologic  map.  The  Olive  deposit  is 
one  of  two  which  may  be  assigned  to  this  set  of  rocks  without 
reservation. 

' It  is  suggested  that  magnetic  observations  might  prove  of.  practical 
value  in  any  future  exploration  of  the  Olive  ore  body. 

BADER  TRACT. 

By  A.  C.  Spencer. 

The  property  known  as  the  Bader  tract  lies  about  9 miles  west  of 
Llano  and  9 miles  south  of  the  Iron  Mountain  mine.  This  parcel 
is  adjoined  upon  the  north  by  a tract  known  as  the  Otto,  the  east 
and  west  property  line  being  somewhat  less  than  2 miles  north  of 
Llano  River.  Iron  ore  has  been  found  at  several  places  along  a 
north  by  northwest  trending  zone  about  500  feet  in  width  and  nearly 
7,000  feet  in  length.  A shaft  in  the  extreme  southwest  corner  of  the 
Otto  tract  encountered  magnetite,  which  represents  the  most  northerly 
known  extension  of  the  Bader  ore  range.  Farther  northwest  there  is 
no  trace  of  any  exploratory  work  such  as  trenches,  and  careful  search 
on  the  part  of  the  geologists  failed  to  reveal  so  much  as  a fragment  of 
magnetite  beyond  the  west  line  of  the  Otto  tract.  That  the  ore  may 
continue  in  this  direction  is  thought  to  be  possible  but  improbable. 

There  is  much  more  granite  north  of  the  Otto  workings  than  on  the 
Bader  tract,  and  the  metamorphic  rocks  are  seriously  broken  and 
interrupted  by  the  granite  intrusions.  This  fact  is  shown  in  a very 
general  way  on  the  geologic  map,  though hnany  slivers  of  schist  are 
present  in  the  areas  which  the  map  shows  as  granite.  The  impos- 
sibility of  adequately  representing  the  actual  relations  of  the  schists 
and  the  granites  has  been  explained  in  former  paragraphs. 

No  importance  can  be  attached  to  any  suggestion  that  might  be 
made  in  the  direction  of  correlating  the  Bader  range  with  other 
occurrences  of  magnetite  in  Llano  County.  There  is  no  adequate 
reason  for  regarding  the  range  as  in  any  way  the  extension  of  the 
Iron  Mountain  ore.  Though  the  trend  of  the  range  would  carry  it  to 
the  ore  on  the  Epperson  tract  3 miles  to  the  northwest,  there  is  a 
wide  area  of  intrusive  granite  north  of  the  Bader,  and  beyond  this 
intrusion  structural  trends  are  rather  northerly  than  northwesterly. 

A sketch  map  (fig.  3)  has  been  prepared  to  show  the  general 
distribution  of  magnetite  occurrences  on  the  Bader  and  the  adjacent 
tracts.  Aside  from  very  shallow  pits  or  trenches  at  various  points, 
the  Bader  range  has  been  explored  only  in  the  vicinity  of  the  northern 
end,  where  the  original  surface  indications  appear  to  have  been  the 
best.  Here  trenches  and  float  ore  extend  for  a total  distance  of  1 ,000 
feet  in  a southerly  direction  from  the  Otto  shaft.  Two  lines  of  outcrop 
about  80  feet  apart  are  noted  in  the  vicinity  of  the  Bader  incline. 


32  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


South  of  the  incline  and  about  110  feet  distant  an  excavation  in  the 
lower  ore  layer  shows  31  inches  of  fairly  clean  ore  dipping  about  30° 
NE.  There  is  also  a 5-inch  rider  lying  2 feet  above  the  principal  ore 
layer  and  separated  from  it  by  feldspathic  gneiss.  In  an  adjacent 
opening  on  the  upper  layer  the  grain  or  layering  of  the  ore  appears  to 
be  nearly  horizontal. 


The  Bader  incline 
reveals  two  ore  layers 
estimated  to  lie  be- 
tween 10  and  15  feet 
apart.  The  dip  of 
these  layers  vanes  from 
20°  to  40°.  The  lower 
ore  may  be  described 
as  gneiss  carrying  thin 
and  discontinuous  lay- 
ers of  magnetite.  This 
lean  material  is  not 
over  16  inches  in  thick- 
ness. The  incline  fol- 
lows the  dip  of  this  ore 
for  about  25  feet  to  a 
point  where  the  slope 
flattens  so  that  the 
workings  cut  across  the 
layering  of  the  gneiss 
and  encounter  the  up- 
per ore  bed.  As  ex- 
posed in  the  sides  of 
the  incline  this  second 
layer  has  a maximum 
thickness  of  20  inches. 

The  dip  length  of  the 
incline  is  estimated  to 
be  about  50  feet.  All 

Figure  3. — Distribution  of  float  and  outcrops  on  Bader  tract  and  Qp0  Qjp  dump  is 

vicinity.  1 Otto  shaft;  2,  Bader  incline;  3,  magnetite  float;  4, 

barite-magnetite  outcrop;  5,  magnetite  float  and  shallow  pits;  6,  layered  to  a marKeCl 
Hickory  Creek  outcrops.  degree,  much  of  it  be- 

ing sharpty  segregated  into  layers  of  more  or  less  granular  magnetite 
and  layers  of  silicate  minerals. 

Standing  on  the  surface  one  may  judge  that  the  lower  of  the  two 
layers  shown  in  the  pits  mentioned  above  is  identical  with  the  upper 
of  the  two  opened  by  the  incline,  though  this  may  not  be  affirmed. 
If  this  identification  be  correct  there  are  at  least  three  ore  layers  at 
this  place,  the  lowermost  being  nowhere  exposed  at  the  surface.  The 
approximate  positions  of  the  last  two  holes  which  have  been  drilled 


IKON  ORES. 


33 


are  given  on  the  sketch  map.  No  record  of  hole  No.  1 is  at  hand. 
The  following  drill  log  is  taken  from  a private  report  by  E.  V. 
DTnvilliers,  who  states  that  this  record  was  furnished  by  G.  M.  Wake- 
field. 


Copy  of  record  of  drill  hole  No.  2,  Bader  location,  Llano  County,  Tex. 


[Signed  by  Fred  A.  Wright,  engineer  in  charge.] 

Stand  pipe 

Granite 

Magnetite  ore  mixed 

Granite 

No  core,  probably  ore 

Granite 

Chloride  rock  and  granite 

Ore 

Granite  schist 

Granite 


Ft.  in. 
1 6 
301  6 
40  3 
29  9 
13 
27 
6 
7 

13 

55  . 


Total  drilled 494 

Angle  of  dip  29.5°  E. 

Strike  of  formation  north-northwest  and  south-southeast. 

Distance  from  cropping  to  point  where  drill  was  placed  600  feet. 

Just  where  the  wagon  track  from  the  south  crosses  the  shallow 
valley  southwest  of  the  Bader  shaft  there  is  a heavy  accumulation 
of  magnetite  float  in  solid  pieces  ranging  up  to  1 foot  in  diameter. 
This  material,  which  is  evidently  derived  from  the  veins  that  are  in 
place  on  the  hill  slope  to  the  east,  is  much  more  prominent  than  the 
float  occurring  along  the  veins  themselves. 

West  of  the  wagon  track  two  lines  of  magnetite  d6bris  may  be  made 
out,  though  it  is  impossible  to  trace  these  lines  for  any  great  distance. 
No  trenching  has  been  done  at  this  place.  About  1,000  feet  west  of 
the  wagon  track  shown  on  the  sketch  map  (fig.  3)  and  just  south  of  an 
east-west  wagon  road  long  abandoned  is  a small  outcrop  of  magnetite 
mixed  with  barite  (BaSOJ.  Only  a few  square  inches  of  this  material 
are  exposed  and  its  relations  are  unknown. 

Along  what  may  be  called  the  main  trend  some  float  ore  may  be 
found  to  a distance  of  500  feet  southeast  of  the  Bader  shaft,  where 
granitic  material  appears  to  interrupt  the  continuity  of  the  ore. 
Though  gneiss  is  present  north  and  east  of  the  small  stream  beyond 
the  granite,  no  ore  fragments  are  found  in  the  soil.  Farther  to  the 
southeast  and  across  the  stream  there  are  no  rock  exposures  for  a 
distance  of  3,000  feet,  though  a few  small  pieces  of  magnetite  were 
noted  northwest  of  the  tributary  plotted  on  the  sketch  map.  South 
of  this  tributary  a series  of  pits  and  small  pieces  of  float  from  place 
to  place  show  the  presence  of  magnetite  for  a distance  of  2,800  feet 
along  a southeast  trend  in  line  with  the  northern  ore  occurrences. 
Also  opposite  the  south  end  of  this  line  of  showings  a second  line  of 
74625°— Bull.  450—11 3 


34  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

ore  indications  is  present.  Along  this  general  zone  the  soil  is  much 
redder  than  elsewhere  in  the  neighborhood. 

On  the  sketch  map  (fig.  3)  two  occurrences  of  magnetite  on  the 
Mason-Llano  road  south  of  Llano  Liver  and  east  of  Hickory  Creek 
are  indicated.  Fragments  of  ore  lying  on  the  surface  are  massive  and 
pure,  but  the  size  of  the  ore  bodies  in  place  can  not  be  judged,  as  no 
work  has  been  done  upon  them. 

The  ore  occurrences  at  the  Hickory  Creek  locality  lie  at  the  end  of 
a curving  tongue  of  more  or  less  hornblendic  gneiss  inclosed  by 
massive  granite,  and  granite  exposed  along  the  river  separates  the 
Hickory  Creek  ore  from  the  nearest  exposures  of  ore  on  the  Bader 
tract. 

No  definite  conclusion  concerning  the  possibilities  of  the  Bader 
tract  can  be  offered.  Compared  with  the  great  cropping  and  the 
abundant  float  at  Iron  Mountain  the  surface  showings  would  seem  to 
be  unimportant.  It  is  beheved,  however,  that  caution  should  be 
exercised  in  accepting  an  unfavorable  point  of  view  in  cases  of  the 
sort  here  presented,  since  experience  in  other  districts  has  shown  that 
the  importance  of  magnetite  ore  bodies  in  gneisses  may  be  seriously 
misjudged  from  surface  indications.  It  is  .suggested  that  the  Bader 
tract  is  worthy  of  more  extensive  exploration  than  it  has  received  up 
to  the  present  time,  and  particularly  that  preliminary  work  in  this 
direction  should  include  a magnetic  survey  of  the  range  which,  as 
already  stated,  has  a length  of  about  7,000  feet.  It  is  thought  that 
dip-needle  observations  might  give  indications  of  ore  in  the  covered 
territory  between  the  two  ends  of  the  Bader  range. 

The  following  are  analyses  of  the  ore  from  the  Bader  property: 


Analyses  of  iron  ore  from  the  Bader  property,  Llano  County,  Tex. 


Metallic 

iron. 

Phosphorus. 

Silica. 

Titanic 

acid. 

Specific 

gravity. 

1 

64. 150 
52. 550 
65. 800 

0. 014 
.019 
.046 

72. 80 
19. 225 

0. 385 
.310 

4. 577 

2 

3 

1.  General  sample  of  outcrop  ore  (Mr.  McCreath).  Report  of  E.  V.  DTnvilliers. 

2.  Sample  representing  4 feet  10  inches  of  the  mixed  lens  ore  from  the  drill  core  on  the  Otto  property. 
Report  of  E.  V.  D’Invilliers. 

3.  Bader  tract.  Report  of  E.  V.  D’Invilliers;  by  Rattle  & Nye,  of  Cleveland,  Ohio. 

IRON  MOUNTAIN. 

By  Sidney  Paige. 

The  Iron  Mountain  prospect  is  located  12  miles  northwest  of  the 
town  of  Llano  and  one  mile  northwest  of  Valley  Spring  post  office. 
The  property  consists  of  640  acres  and  is  owned  by  Robert  H.  Down- 
man,  of  New  Orleans,  La. 


IRON  ORES. 


35 


The  ore  body  caps  a low  mound  slightly  above  the  elevation  of  the 
surrounding  country,  and  trends  about  N.  60°  W.  in  a gently  curving 
line.  The  surface  outcrop  has  a length  of  about  114  feet  and  a width 
of  22  feet  at  its  center.  It  is  slightly  narrower  at  the  northwest  end 
and  narrows  down  to  about  6 feet  at  the  southeast  end.  (See  fig.  4.) 
A granite  intrusion  cuts  across  the  mass  at  the  northwest  end,  appar- 


Figure  4.—  Surface  crop  and  underground  workings  at  Iron  Mountain  prospect. 


ently  cutting  off  the  ore.  Covered  surface  prevents  observations  on 
the  southeast  end. 

The  ore  body  as  revealed  at  the  surface  is  a nearly  vertical  mass  of 
very  pure  magnetite.  Along  its  south  side  schists  are  exposed  in 
several  small  cuts.  They  strike  northwest  with  the  ore,  but  in  dip 
do  not  accord  with  the  dip  of  the  mass.  (See  figs.  4 and  5.)  On  the 
north  side  a gneissoid  rock  of  granitic  type  forms  the  wall.  It  is 
believed  to  be  intrusive  into  the  ore,  but  is  an  older  intrusion  than 


36  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


gneissoid  granite 


Schist 


that  of  the  granite  which  cuts  across  the  northwest  end.  Unfortu- 
nately the  surface  cover  has  rendered  the  exact  surface  relations  of  the 
ore  body  obscure ; also  the  complex  intrusion  of  granite  into  the  schists, 
a condition  described  in  an  earlier  part  of  the  report,  has  at  this  local- 
ity obscured  the  original  relations  of  the  ore  to  the  inclosing  rock. 

Both  northwest  and  southeast  of  the  ore  body  the  surface  is  covered 
with  soil  and  only  occasional  outcrops  of  weathered  material  may  be 
seen.  About  450  feet  northwest  a small  outcrop  of  iron  in  schist  was 
noted;  granite,  gneissoid  granite,  and  schist  are,  however,  evidently 

present  in  a complex  mixture. 
Float  ore  can  be  found  both  north- 
west and  southwest  of  the  crop, 
but  much  of  this  in  the  near  vicin- 
ity of  the  ore  mass  is  evidently 
derived  from  it  and  has  during 
erosion  been  carried  to  its  present 
position.  Some  float  ore  derived 
from  the  overlying  Cambrian  sand- 
stone and  occasionally  carrying 
fossils  must  not  be  confused  with 
the  magnetite  float  of  the  pre- 
Cambrian  ores. 

A study  of  the  plan  and  sections 
(figs.  4 and  5)  will  show  clearly 
what  is  known  of  the  structure  of 
the  body  as  revealed  by  develop- 
ments. A shaft  was  sunk  near 
the  southwest  wall  of  the  ore  body. 
A crosscut  has  been  driven  at  the 
50-foot  level,  showing  25  feet  of 
solid  ore.  This  crosscut  was  con- 
tinued 54  feet.  After  passing 
through  the  25  feet  of  ore  a narrow 
mass  of  granitic  schistose  material 
was  encountered,  after  which  ore  was  again  found.  This  second  body 
was  confined  largely  to  the  floor,  and  a winze  was  sunk  in  ore. 
(See  fig.  5.) 

On  the  50-foot  level  two  drifts  were  driven.  (See  fig.  4.)  At  the 
time  of  the  writer’s  visit  the  northwest  drift  had  been  opened  30  feet, 
with  no  solid  ore  in  any  part  of  the  working.  Since  that  time  the 
drift  is  reported  to  have  been  driven  to  73  feet,  with  ore  in  the  roof 
and  northwest  wall,  at  this  point. 

The  southeast  drift  at  the  time  of  the  writer’s  visit  had  been 
opened  60  feet,  with  solid  ore  on  the  south  wall  to  a point  30  feet  ± 
from  the  center  of  the  crosscut.  Since  that  time  the  drift  is  reported 
to  have  been  driven  to  a point  89  feet  9 inches  from  the  center  of  the 


Q | | so  Feet 

Figure  5. — Vertical  section  of  ore  body  at  Iron 
Mountain  prospect. 


IRON  ORES. 


37 


Before  faulting 


Crosscut,  and  to  have  had  ore  on  the  south  wall  the  entire  distance; 
and  at  that  point  is  reported  to  have  ore  on  both  walls  and  in  the  roof. 

At  the  100-foot  level  crosscuts  and  drifts  were  run,  as  shown  on 
the  plan  (fig.  4),  but  ore  was  not  encountered  under  the  vertical 
mass.  The  country  rock  is  a mixture  of  schist  and  granite.  A raise 
was  made  from  the  100-foot  level  to  connect  with  the  winze,  and 
revealed  16  feet  of  ore  in  a nearly  flat-lying  body  of  schist,  grading 
downward  into  lean  ore  and 
granite.  The  schists  con- 
taining the  ore  dipped  at  a 
low  angle  to  the  east. 

The  crosscut  shown  on 
the  100-foot  level  was 
driven  55  feet,  but  encoun- 
tered no  ore.  At  the  time 
of  the  writer’s  visit  the  drift 
on  the  100-foot  level  had 
been  driven  62  feet,  but  no 
ore  found.  Since  that  time 
this  drift  is  reported  to  have 
been  driven  to  a point  93 
feet  from  the  center  of  the 
crosscut,  and  to  have  found 
at  that  point  a lump  of  dis- 
connected ore  weighing 
about  500  pounds. 

The  relations  described 
above  may  be  hypothetically 
explained  as  follows:  The 
vertical  mass  of  iron  ore 
is  a layered  body  with  the 
layering  vertical.  It  is  be- 
lieved that  formerly  it  oc- 
cupied a position  in  accord 
with  the  schists,  as  does 
the  mass  exposed  i n the 
winze.  F aulting  is  believed 
to  have  taken  place  on 
both  south  and  north  sides,  though  evidence  for  the  latter  is  not  as 
strong  as  for  the  former.  (See  fig.  5.)  Several  facts  point  to  this 
conclusion.  The  schists  on  the  south  side  dip  sharply  downward  at 
their  contact  with  the  iron,  suggesting  fault  drag,  and  a band  of  soft 
chlorite-like  material  about  2 inches  wide  is  found  at  the  contact. 
.The  drag  was  observed  both  at  the  surface  and  at  the  50-foot  level. 
The  gouge  material  was  not  so  well  developed  at  this  level.  From 
the  very  fact  also  that  the  layering  of  the  ores  of  the  region  has 


Has  been  worn  away 


After  faulting 

Figure  6.— Ideal  section  showing  relation  of  faulting  to 
folding  and  erosion. 


38  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

elsewhere  been  invariably  parallel  to  the  schistosity  the  discordance 
here  is  excellent  evidence  of  faulting.  At  the  50-foot  level  on  the 
north  side,  there  is  also  a suggestion  of  faulting. 

The  direction  and  dip  of  these  hypothetical  faults  may  be  some- 
what different  from  those  indicated  by  the  plan  and  section,  but  the 
structural  results  of  their  presence  are  believed  to  be  as  presented. 

The  vertical  iron  mass,  therefore,  is  on  the  downthrow  side  of  both 
faults  No.  1 and  No.  2.  The  fault  plane  was  for  a distance  parallel 
to  the  limb  of  a fold  and  accounts  for  the  vertical  position  of  the  large 
iron  mass  and  its  peculiar  relation  to  the  flat  iron  bed.  The  differ- 
ence in  thickness  between  the  flat  bed  and  the  vertical  bed  may  be 


Figure  7. — Stereogram  illustrating  condition  which  would  exist  if  the  north 
fault  passed  vertically  but  at  an  angle  to  the  strike  of  the  fold. 


accounted  for  by  supposing  a certain  amount  of  movement  to  have 
taken  place  in  a horizontal  direction,  bringing  a thinner  portion  of 
the  layer  against  a thicker  portion.  Intrusion  of  granite  probably 
preceded  this  faulting.  There  is  some  reason  to  believe,  however, 
that  the  fault  on  the  north  side  was  accompanied  or  followed 
by  granite  intrusion.  Figure  6 is  an  ideal  sketch  of  the  probable 
conditions  before  and  after  faulting,  and  figure  7 is  a stereogram 
showing  the  relation  which  might  exist  if  the  north  fault  plane  passed 
at  an  angle  to  the  strike  of  the  bed. 

Besides  the  development  by  shaft  and  tunnels  above  described  the 
property  has  been  prospected  by  several  diamond-drill  holes.  They 
will  be  described  in  the  order  of  their  drilling. 

The  first  hole,  located  200  feet  S.  57°  W.  of  the  shaft  and  inclined 
37°  toward  it,  was  drilled  to  a depth  of  169  feet.  Two  feet  of  ore 
was  reported  at  108  feet.  This  hole,  to  have  reached  the  vertical 
plane  of  the  ore  body,  should  have  been  drilled  250  feet.  It  would 
have  cut  the  plane  at  a depth  of  150  feet. 


IRON  ORES. 


39 


The  second  hole,  located  488  feet  S.  72°  E.  from  the  northeast 
corner  of  the  shaft,  was  drilled  S.  4°  W.  at  an  angle  of  43°.  A foot 
of  lean  ore  was  struck-  at  18  feet.  The  drill  jammed  at  225  feet. 
Another  hole  at  this  same  locality  was  drilled  290  feet  S.  77°  W. 
with  a dip  of  49°.  its  record  follows: 

Record  of  hole  drilled  in  Iron  Mountain  iron  'property , Llano  County , Tex. 


Ft. 

in. 

Ft. 

in. 

Lean  ore 

14 

11 

to 

16 

Pink  granite 

16 

to 

25 

Decomposed  material 

25 

to 

25 

8 

Granite 

25 

8 

to 

31 

4 

Black  schist,  little  magnetite 

31 

4 

to 

35 

8 

Granite 

35 

8 

to 

198 

1 

Black  schist  and  granite 

198 

1 

to 

199 

Granite 

199 

to 

215 

5 

Ore 

215 

5 

to 

216 

8 

Hole  253  feet  deep  on  October  8,  1909,  without  commercial  ore. 

Next,  a hole  was  drilled  500  feet  northeast  of  the  shaft.  It  was 
put  down  500  feet.  No  ore  was  struck. 

Then  a hole  was  drilled  on  this  same  line,  but  only  216  feet  from 
the  shaft.  It  dipped  60°  toward  the  shaft  and  was  drilled  to  a depth 
of  606  feet.  No  ore  was  struck. 

A hole  approximately  1,400  feet  northeast  of  the  shaft  and  east  of 
Johnson  Creek  was  down  600  feet  at  the  end  of  March,  1909,  without 
striking  commercial  ore.  It  was  drilled  toward  the  shaft  at  an  angle 
of  45°. 


Analyses  of  ore  from  Iron  Mountain,  Llano  County,  Tex. 


Metallic 

iron. 

Phosphorus. 

Silica. 

Specific 

gravity. 

l 

65.40 

67.60 

65.45 
66. 53 
64. 90 
58. 87 

61.45 
67.70 
66. 10 
63.  23 
66. 82 
66. 30 

0. 069 
.093 
.061 
Not  det. 
Not  det. 
Not  det. 
Not  det. 
0.045 
.034 
.008 
Trace. 
0. 146 

4.695 

4.690 

4.724 
4. 677 

2 

3 

4 

6 

8 

9 

10  a 

4.70 

4.65 

6.30 

11  b 

12  c 

a Sulphur,  trace.  *>  Sulphur,  0.30.  c Sulphur,  0.04. 


1.  General  sample  of  surface  ore.  Private  report  of  E.  V.  D’lnvilliers. 

2.  Sample  125  pieces  of  ore  at  depth  of  50  feet  in  shaft.  Report  of  E.  V.  D’Invilliers. 

3.  Surface  ore  clippings  large  bowlders  (sampled  by  representative  of  McCreath).  Report  of  E.  V. 
D’Invilliers. 

4.  Surface  ore  main  exposure  (sampled  by  representative  of  McCreath,  1889).  Report  of  D’Invilliers. 

5.  From  shaft  8 feet  deep,  south  side  main  exposure.  (McCreath.)  Report  of  D’Invilliers. 

6.  From  shaft  12  feet  deep,  north  side  of  main  exposure,  lower  8 feet  of  ore.  (McCreath.)  Report  of 
D’Invilliers. 

7.  150  yards  east  of  main  exposure,  from  cut  4 feet  deep.  (McCreath.)  Report  of  D’Invilliers. 

8.  From  shaft  at  main  exposure,  ore  from  lower  depth  than  5 or  6,  chiefly  magnetic.  Report  of  D’Invil- 
liers. 

9.  Iron  Mountain  tract,  sampled  and  analyzed  by  Rattle  & Nye.  Report  of  D’Invilliers. 

10.  50-foot  level.  Iron  Mountain  mine;  taken  by  Robert  Linton,  of  Atwater,.  Linton  & Atwater,  mining 
engineers,  for  Johnston,  Elliot  & Co.,  of  Dallas,  Tex. 

11.  50-foot  level,  Iron  Mountain  mine;  taken  by  Robert  Linton,  for  Johnston,  Elliot  & Co.,  of  Dallas, 
Tex. 

12.  7 feet  of  new  ore  on  east  wall  of  winze,  48-foot  level,  sampled  by  William  B.  Phillips,  Rinaldo  Wil- 
liams, analytical  chemist,  Birmingham,  Ala. 


40  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

It  would  seem  advisable  to  confine  prospecting  largely  to  the  north 
side  of  the  line  of  strike  of  the  ore  body.  If  it  can  be  shown  that  the 
flat  bed  has  considerable  extension  in  a northwest-southeast  direc- 
tion and  also  on  the  dip,  a large  body  of  ore  may  be  present.  If 
underground  work  is  to  be  continued  it  would  seem  advisable  to  make 
a raise  from  the  end  of  the  east  drift  on  the  100-foot  level,  at  the 
point  where  iron  was  struck,  to  discover  the  presence  or  absence  of 
the  bed.  A magnetic  survey  of  the  territory  adjacent  to  the  ore 
body  would  be  of  value. 

KEYSER-JONES  TRACT. 

By  A.  C.  Spencer. 

In  Mason  County,  about  4J  miles  south  and  somewhat  west  of 

Castell,  magnetite  float  and  ore  out- 
crops occur  at  several  places  within 
the  drainage  basin  of  Keyser  Creek, 
otherwise  known  as  Old  Place  Creek. 
The  relative  locations  are  shown  on 
the  accompanying  sketch  map  (fig.  8.) 
The  most  noteworthy  showing  is  on 
a subdivision  of  the  tract  belonging 
to  Judge  J.  H.  Jones,  of  Mason.  Here 
massive  magnetite  outcrops  along  a 
low  hillock  for  a total  distance  of  75 
feet,  the  maximum  observed  widfh 
of  ore  being  about  4 feet.  The  ore 
is  distinctly  layered  in  its  make-up 
and  is  rather  siliceous.  The  trend  of 
the  cropping  is  about  N.  45°  W.  No 
rocks  are  exposed  within  several  hun- 
dred feet  except  at  a point  100  feet 

Figure  8.— Magnetite  prospects  on  Keyser-  southeast  of  the  Ore  where  micaceOUS 
Jones  tract,  southwest  of  Castell. 

gneiss  was  noted.  About  a quarter  of 
a mile  northwest  along  the  general  strike  of  the  ore  a low  hill  is  formed 
of  hornblende  schist.  If  the  outcrop  at  Iron  Mountain  be  excepted, 
this  is  the  largest  surface  showing  of  magnetic  iron  ore  in  the  Llano 
district.  At  present,  however,  there  would  be  no  adequate  induce- 
ment to  warrant  the  expense  of  drilling  at  this  point,  though  in  the 
future  such  exploration  might  be  advisable. 

A second  fairly  good  showing  of  magnetite  may  be  seen  on  a hill- 
top somewhat  less  than  half  a mile  east  and  a little  south  of  Jones’s 
house  above  the  tank  (stock  reservoir) . This  ore  is  accompanied  by 
red- weathering  gneiss  or  schist,  a curving  band  of  which  may  be 
traced  to  the  northeast  and  east  across  the  two  roads  shown  on  the 
sketch  map.  Magnetite  float  may  be  found  from  place  to  place  along 


IRON  ORES.  41 

this  red  band,  but  one  does  not  gain  the  impression  that  excavation 
is  likely  to  reveal  any  body  of  ore. 

A mile  or  more  farther  south  minor  amounts  of  magnetite  may  be 
found  in  association  with  highly  metamorphic  schists,  and  in  this 
case  outcrops  are  adequate  for  a decision  that  no  deposits  of  economic 
importance  are  to  be  expected.  On  the  whole  the  possibilities  of 
the  tract  seem  to  depend  upon  the  Jones  outcrop. 

GOODWIN  PROSPECT. 

By  Sidney  Paige. 

About  miles  S.  55°  W.  of  Baby  head  post  office,  small  outcrops 
of  iron  ore  may  be  seen  on  Mr.  Goodwin’s  place.  The  rocks  are 
believed  to  belong  to  the  lighter  (lower)  gneiss  and  schist  series 
(Valley  Spring  gneiss),  and  are,  as  is  almost  invariably  the  case, 
more  or  less  intruded  by  granite. 

A short  distance  north  of  Mr.  Goodwin’s  house  a small  trench 
reveals  a foot  or  two  of  lean  hematite  ore  banded  with  quartz  and 
feldspar,  the  latter  minerals  forming  a very  fine  sugar-grained  aggre- 
gate. The  individual  thin  iron  layers  swell  and  pinch  in  an  irregular 
manner.  What  appears  to  be  secondary  quartz  is  introduced  in 
bands  along  the  schistosity  in  considerable  abundance.  The  hema- 
tite is  feebly  magnetic,  and  octahedral  faces  can  be  detected  among 
the  crystals.  The  mineral  is  probably  martite,  a pseudomorph  of 
magnetite. 

Farther  west  over  the  ridge  may  be  seen  white  schists  of  very  even, 
fine,  sugar-grained  texture,  carrying  finely  disseminated  hematite 
in  minute  grains.  Abundant  orthoclase  feldspar,  with  quartz  and 
muscovite,  make  up  the  rock,  which  is  believed  to  be  a metamorphic 
sediment. 

About  1,000  feet  S.  10°  E.  from  the  house  a shallow  pit  in  the 
schists  reveals  a small  bed  of  magnetite  lying  nearly  flat  and  striking 
nearly  east  and  west.  About  9 or  10  inches  of  ore  is  exposed  for  50 
feet.  The  dip  is  to  the  south,  more  pronouncedly  so  at  the  west  end. 
Considerable  garnet  and  abundant  quartz  with  some  pyrite  are  the 
gangue  minerals. 

Less  than  1,000  feet  west  of  the  locality  and  S.  37°  W.  from  the 
house  just  described,  a small  pit  shows  an  apparently  vertical  bed  of 
magnetite  and  quartz  with  1 or  2 feet  of  lean  ore.  This  deposit  can 
be  traced  for  100  feet  in  the  trend  of  the  ridge.  Locally  there  is  an 
indication  of  about  5 feet  of  ore.  The  north  end  of  the  outcrop  is 
apparently  cut  off  by  a swing  in  the  beds  of  pink  schist. 

No  encouragement  can  be  given  that  these  deposits  have  any 
commercial  value. 


42  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

PARKHILL  PROSPECT. 

By  Sidney  Paige. 

About  1 mile  east  by  south  of  the  summit  of  Horse  Mountain  a 
small  quantity  of  ore  may  be  seen  about  2,300  feet  north  of  and 
between  the  forks  of  two  creeks.  The  bed  strikes  N.  55°  W.,  dips 
20°  S.,  and  is  about  2 feet  thick.  The  magnetite  is  admixed  with 
quartz  and  red  feldspar,  and  the  pit  reveals  decided  irregularity  in 
thickness.  The  deposit  does  not  seem  worthy  of  further  prospecting 
at  the  present  time. 

About  1 mile  northwest  of  Miller  Mountain  and  east  of  the  main 
north  and  south  Babyhead  road,  a small  trench  shows  a foot  or  a 
foot  and  a half  of  lean  ore  in  schist.  The  country  rock  trends  about 
N.  30°  W.  and  dips  south.  This  opening  and  another  a short  distance 
northwest  of  it  do  not  offer  any  inducement  to  further  prospecting. 

IRON  DEPOSITS  NEAR  CASTELL. 

By  A.  C.  Spencer. 

Castell  post  office  is  situated  on  Llano  River  18  miles  west  of  Llano. 
North  of  the  river  within  the  radius  of  a few  miles  there  are  showings 
of  iron  ore  at  several  places  which  may  be  described  in  two  groups — 
the  Deep  Creek  deposits  and  the  Elm  Creek  deposits.  The  ores  of  the 
Deep  Creek  and  Elm  Creek  drainage  basins  are  regarded  as  of  no 
probable  value,  because  the  deposits,  though  extensive,  are  both  lean 
and  thin.  At  the  same  time  by  way  of  caution  against  absolute  dis- 
paragement it  is  to  be  noted  that  such  development  work  as  has  been 
done  is  negligible,  so  that  the  impressions  gained  by  the  geologists 
have  been  derived  from  very  imperfect  surface  showings.  With  due 
allowance  made  for  this  condition,  the  opinion  may  be  expressed  that 
although  future  work  may  lead  to  the  discovery  of  ore  masses  of 
sufficiently  high  grade  to  warrant  mining  operations,  such  ore  bodies 
will  not  prove  to  be  of  large  size,  so  that  it  can  not  be  expected  that 
any  large  mines  will  ever  be  developed  in  the  combined  field  of  Deep 
and  Elm  creeks. 

DEEP  CREEK  ORES. 

Deep  Creek  (fig.  9)  joins  Llano  River  about  li  miles  above  the 
Castell  ford.  From  the  river  the  creek  valley  extends  a mile  west  to 
an  elbow,  above  which  it  has  a general  north-south  course  for  some- 
what more  than  a mile  before  turning  again  to  the  west  about  one- 
fourth  mile  north  of  the  Mason  stage  road. 

The  magnetite  deposits  occur  in  the  Deep  Creek  valley  near  the 
lower  elbow  and  again  north  of  the  Mason  road. 

The  magnetite  showings  near  the  elbow  of  Deep  Creek  are  disposed 
along  a line  about  a mile  in  length.  Downstream  from  the  bend  the 


IRON  ORES. 


43 


presence  of  a little  ore  is  noted  on  the  north  bank  of  the  creek,  and 
toward  the  southeast  heavy  float  is  noted  at  two  points.  At  these 
localities  the  ore  is  massive  and  nearly  pure,  the  only  minerals  present 
besides  magnetite  being  a little  feldspar  and  mica.  The  manner  of 
occurrence  is  not  evident,  but  the  three  localities  lie  along  a line 
trending  northwest  and  crossing  the  creek  both  below  and  above  the 
elbow.  Opposite  the  elbow  none  is  noted,  but  west  of  the  creek  it 
again  appears  and  abundant  float  may  be  traced  along  the  hill  slope 


north  of  a small  drain.  About  1,800  feet  above  the  mouth  of  this 
drain  the  line  of  the  ore  crosses  the  shallow  valley  and  turns  back  upon 
itself.  The  hook-shaped  outcrop  may  be  taken  as  evidence  that  the 
ore  occurs  as  a conformable  layer  in  the  local  schists  and  that  the  rocks 
are  here  thrown  into  a low  arch  or  anticline. 

A few  outcrops  of  feldspathic  schist  in  the  neighborhood  exhibit 
strikes  and  dips  which  bear  out  this  impression  of  structure. 

Though  the  exposures  of  ore  are  yery  inadequate,  they  serve  to 
convey  the  impression  that  the  iron  mineral  may  be  distributed 


44  MINERAL,  RESOURCES  OF  LLaXO-BURNET  REGION,  TEXAS. 

through  3 or  4 feet  of  rock,  and  that  the  reef  is  made  up  of  layers  of 
rock  and  ore  from  6 to  10  inches  thick.  Some  of  the  component 
layers  are  high-grade  ore;  others  are  platy  aggregates  of  magnetite 
and  siliceous  minerals;  still  others  carry  but  little  iron. 

North  of  the  Mason  road,  east  and  north  of  Deep  Creek,  magnetite 
is  found  at  several  points.  A short  distance  north  of  the  road  a few 
isolated  fragments  of  good  ore  were  noted.  Then  a quarter  of  a mile 
or  so  to  the  northwest  there  has  been  some  prospecting.  Natural 
outcrops,  shallow  pits,  and  float  lead  to  the  recognition  of  a curving 
magnetite  range  perhaps  half  a mile  in  length  (fig.  9).  There  are 
evidently  two  parallel  reefs  along  part  of  the  range  which  are  esti- 
mated to  be  less  than  20  feet  apart,  measured  across  the  layering. 
The  curving  outcrop  and  observed  dips  show  that  the  ore  and  asso- 
ciated schists  are  gently  folded.  The  dips  are  low  to  the  east,  or, 
locally  at'  the  turn,  approximately  south. 

The  ore  appears  to  be  rather  lean,  much  of  it  showing  garnet  mixed 
with  magnetite.  Specimens  were  seen  which  are  composed  of  alter- 
nate thin  layers  of  fairly  clean  magnetite  and  of  quartz.  The  garnet- 
bearing  reefs  vary  in  thickness  from  18  inches  to  3 feet. 

The  ore  reefs  are  by  no  means  continuous  along  the  strike.  Part, 
but  certainly  not  all,  of  the  observed  discontinuity  is  due  to  the  pres- 
ence of  irregular  intrusive  masses  of  granite,  both  fine  and  coarse 
grained  varieties  being  present. 

North  of  the  occurrences  mentioned  in  the  foregoing  paragraph,  at 
the  locality  marked  A on  the  sketch  map,  figure  9,  there  is  a rather 
noteworthy  showing  of  magnetite  float.  In  addition  to  good-sized 
chunks  of  pure  ore  there  is  an  interesting  exhibition  of  coarsely 
crystalline  material  composed  of  quartz,  pink  feldspar,  and  magnetite 
in  various  proportions.  This  material  is  not  exposed  in  place,  but  it 
has  every  appearance  of  being  pegmatite  (extremely  coarse  granite) 
of  very  siliceous  and  ferruginous  composition,  and  is  therefore 
believed  to  be  intrusive  in  its  nature.  Magnetite-bearing  pegmatites 
were  noted  in  small  amounts  at  many  places  in  the  Llano  district,  but 
no  other  instance  of  any  great  amount  of  the  mineral  in  this  association 
was  seen.  Though  the  ore  at  this  particular  place  is  regarded  as 
almost  certainly  of  igneous  origin,  it  is  not  regarded  as  possible  to  use 
this  conclusion  in  any  definite  way  in  working  out  the  general  origin 
of  the  iron  ores  of  the  district. 

If  the  layered  ores  of  Deep  Creek  valley  are  not  merely  ferruginous 
strata  which  have  suffered  simple  metamorphism  in  company  with 
sedimentary  beds  originally  associated  with  them,  as  suggested  by  Mr. 
Paige  elsewhere  in  this  report,  they  were  formed  by  some  process  the 
nature  of  which  can  not  be  stated — some  process,  as  yet  unrecognized, 
involving  secondary  rather  than  primary  or  original  segregation. 


IRON  ORES. 


45 


ELM  CREEK  ORES. 

The  distribution  of  magnetite  showings  northeast  and  east  of  Castell 
is  given  on  the  sketch  map  (fig.  10).  It  should  be  noted  that  the  area 
shown  on  this  map  overlaps  that  of  the  Deep  Creek  sketch  map  (fig.9). 

Between  the  southward-flowing  portion  of  Elm  Creek  and  the  next 
considerable  valley  to  the  east  the  land  rises  to  form  a rolling  plateau. 
Along  the  west  edge  of  this  plateau,  just  at  the  break  to  the  Elm  Creek 
slope,  or  locally  somewhat  down  this  slope,  an  iron-bearing  reef  may 


Figure  10. — Distribution  of  magnetite  near  Elm  Creek,  northeast  of  Castell.  A, 
Area  shown  in  figure  11;  B,  area  shown  in  figure  12. 


be  followed  by  means  of  float  and  occasional  outcrops  for  a distance  of 
1A  miles.  The  trend  of  this  reef  is  nearly  north-south,  the  north  end 
(in  the  form  of  a hook)  being  situated  1 mile  northeast  of  the  Lang 
house.  Though  there  is  no  difficulty  in  following  the  lead  by  means 
of  the  surface  showings,  the  ore  is  seen  not  to  be  really  continuous, 
being  interlayered  with  the  associated  feldspathic  gneisses.  Locally 
there  are  evidences  of  two  ore  layers,  neither  one  of  which  can  be  more 
than  2 feet  thick.  Dips  are  uniformly  low  to  the  east.  All  of  the  ore 


46  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


is  lean  in  appearance,  and  scarcely  any  of  it  would  analyze  above  30 
per  cent  of  iron. 

The  south  end  of  this  line  of  croppings  is  north  of  a small  drain  in 
the  northeast  corner  of  Dr.  Donges’s  pasture,  and  for  a distance  of 
about  1,000  feet  to  the  south  along  this  trend  there  are  no  signs  of  mag- 
netite. West  of  the  trend,  however,  minor  amounts  of  float  were 
noted  at  two  points,  and  a 6-inch  seam  of  ore  outcrops  in  the  stream 
bank  at  a point  indicated  on  the  sketch  map  (fig.  10).  In  the  vicinity 
of  this  stream  the  rocks  appear  to  be  greatly  disturbed,  as  there  are 
great  variations  in  strikes  and  dips  from  place  to  place.  At  the  6-inch 
capping  noted  above  the  dip  is  about  45°  XXE. 

Directly  east  of  the  exposure  last  mentioned  and  west  of  the  Donges- 
Ebers  property  line,  on  the  edge  of  the  plateau,  a flat-lying  layer  of  lean 
ore  about  2 feet  thick  has  been  stripped  of  its  original  cover  over  an 
area  of  perhaps  250  square  feet.  This  flat  constitutes  the  western 
limit  of  a line  of  outcrops  extending  in  an  easterly  direction  along  the 
southern  break  of  the  plateau  for  a distance  of  approximately  3,000 
feet.  The  western  exposure  lies  due  south  of  the  termination  of  the 
north-south  line  of  croppings  already  described,  the  barren  interval 
between  being  about  1,200  feet. 

Locally  along  this  east-west  trend  there  are  indications  of  magne- 
tite in  two  layers,  perhaps  20  feet  apart,  but  usually  there  is  only  one 
layer.  At  the  east  end  of  the  line  of  outcrops  the  ore  laj'er  is  complexly 
folded  and  also  disrupted  by  granite  intrusions.  Along  the  cropping 
the  dip  is  to  the  north  at  a very  low  angle. 

Wherever  exposed,  the  ore  is  lean  in  appearance,  because  of  the 
amount  of  quartz  and  potash  feldspar  which  it  contains.  Its  thick- 
ness was  nowhere  observed  to  be  greater  than  2 feet,  and  nearly  every- 
where it  is  less  than  18  inches.  The  associated  rocks  are  feldspar 
gneisses  and  granite.  At  many  points  thin  sill-like  masses  of  coarse 
granite  (pegmatite)  lie  under  the  ore  layer,  but  no  genetic  relation  may 
be  made  out  between  this  rock  and  the  magnetite. 

Four  samples  collected  to  represent  the  ore  of  this  east  ward- trending 
outcrop  may  be  taken  as  typical  of  the  ores  of  the  Elm  Creek  occur- 
rences, since  there  is  very  close  resemblance  in  the  material  observed 
in  all  of  the  several  localities.  Samples  1 to  3 came  from  near  the 
east  end  of  the  line  of  outcrops  and  sample  4 from  a point  near  where 
the  reef  crosses  the  wagon  track. 

. Analyses  of  Elm  Creek  iron  ores,  Llano  County,  Tex. 

[R.  C.  Wells,  analyst,  United  States  Geological  Survey.] 

1.  2.  3.  ! 4. 


Fe 25.68  26.04  14.60  24.70 

Si02 54.56  52.23  62.53  55.36 

Un Trace.  .06  None.  Trace. 

P .04  . 05  . 01  .05 

S .06  .10  . 04  . 07 

Ti02 .10  i .20  .11  i .10 


IRON  ORES. 


47 


In  the  northern  part  of  Christian  Schneider’s  pasture,  about  a quar- 
ter of  a mile  south  of  the  east-west  ore  belt  described  above,  similar 
lean  material  occurs  within  an  area  about  half  an  acre  in  extent.  The 
ore  evidently  occurs  as  a layered  deposit  thrown  into  shallow  folds, 
though  the  rock  layers  are  not  exposed  with  sufficient  completeness 
to  clearly  reveal  the  structural  details  (figs.  10  and  11).  Considerable 
intrusive  granite  is  noted  within  the  area,  including  the  different  out- 
crops of  ore. 

The  thickness  of  ore  observed  varies  from  15  inches  to  3 feet. 

South  of  Elm  Creek  ore  is  to  be  observed  at  four  points.  Near  the 
north  side  of  Schneider’s  horse  pasture  is  a single  outcrop  of  an  ore 


Figure  11— Distribution  of  magnetite  showings  in  northern  part  of  Schneider’s  pasture 

{A,  fig.  10). 


layer  2 feet  thick.  East  of  this  a small  amount  of  float  is  encountered 
along  the  wagon  track,  and  as  the  local  trends  are  east  and  west  it  may 
be  suggested  that  prospecting  would  reveal  a more  or  less  continuous 
lead  between  these  two  points.  A short  distance  north  of  the  Schnei- 
der house  the  presence  of  float  suggests  the  existence  of  a nearly  east 
and  west  trending  ore  layer  extending  west  of  the  wagon  track  for  per- 
haps 200  feet.  The  fourth  locality  south  of  Elm  Creek  is  on  the  hill- 
top between  the  creek  and  the  river,  partly  within  the  Schneider  tract, 
but  extending  across  the  east  boundary  line.  The  rocks  are  layered 
feldspathic  schists,  weathering  of  which  produces  a very  red  soil.  The 
ore,  which  is  interlayered  with  the  schist,  may  be  seen  to  have  a local 


48  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

thickness  of  18  inches,  though  it  is  thinner  in  places.  A sample  of  the 
best-looking  material  in  sight  gave  the  following  analysis : 

Analysis  of  Elm  Creek  iron  ore , Llano  County,  Tex. 


Iron 35.  40 

Silica 34.  68 

Manganese Trace. 

Phosphorus .03 

Sulphur 04 

Titanium  oxide 15 


The  ore  layer  may  be  traced  by  means  of  outcrops  and  float  for  a 
distance  of  approximately  600  feet  along  a general  northeast  course, 
but  the  stronger  showings  are  confined  to  the  southwest  part  of  the 
area  of  outcrop.  Here  the  ore  and  the  associated  rocks  are  evidently 
folded  to  a considerable  degree,  and  possibly  have  been  duplicated  by 
dislocation. 

About  2 miles  east  of  Castell  and  1 mile  east  of  the  locality  de- 
scribed in  the  foregoing  paragraph  magnetite  is  found  in  two  places 
about  1,000  feet  apart.  (See  figs.  10  and  12.) 

On  the  north  the  ore  may  be  traced  along  a low  ridge  in  a southerly 
direction  for  a distance  of  825  feet.  The  reef  as  seen  in  natural 
exposures,  no  trenching  having  been  done,  may  have  a maximum 
thickness  somewhat  in  excess  of  6 feet,  though  throughout  much  of 
its  length  it  is  almost  certainly  thinner.  No  sample  was  analyzed, 
but  from  the  general  nature  of  the  material  it  can  hardly  carry  above 
35  to  40  per  cent  of  iron.  The  better  portions  of  the  ore  closely 
resemble  lean  portions  of  the  Iron  Mountain  ore.  The  reef  is  cut 
across  by  two  granite  dikes  30  and  50  feet  wide.  The  dip  of  the  ore 
was  not  satisfactorily  determined,  though  it  is  probably  low  toward 
the  east. 

South  from  the  last  outcrop  is  a belt  of  red  soil  within  which,  at  a 
distance  of  930  feet,  strong  magnetite  float  again  appears.  Near  by  is 
an  outcrop  of  lean  ore  dipping  about  10°  E.  From  this  outcrop  there 
are  almost  continuous  showings  along  a curving  zone  for  a distance  of 
400  feet  or  more.  Beyond  where  the  zone  turns  from  south  to  west 
the  ore  lies  nearly  flat  and  is  obscurely  exposed  for  a width  of  about 
50  feet.  The  material  is  of  very  lean  appearance.  It  can  hardly 
be  more  than  3 feet  thick  and  is  probably  thinner. 

LIVELY  TRACT. 

By  A.  C.  Spencer. 

The  Lively  property  lies  somewhat  more  than  1 mile  southeast  of 
Iron  Mountain  and  three-fourths  of  a mile  southwest  of  Valley 
Spring.  There  has  been  no  development,  and  the  showing  is  con- 
fined to  magnetite  float  in  the  wagon  road  northeast  of  Johnson 
Creek.  The  position  of  this  locality  is  near  a line  joining  the  ore  at 


IRON  ORES. 


49 


Iron  Mountain  to  .the  northwest  and  the  Becton  ore  4 miles  to  the 
southeast.  Although  the  three  localities  are  thus  in  alignment  there 
is  no  adequate  basis  for  the  suggestion  of  any  connection  between 
the  several  deposits  or  for  any  expectation  that  intermediate  deposits 
are  likely  to  be  discovered. 

Between  the  Lively  ore  and 
Iron  Mountain  the  ancient 
gneisses  are  buried  beneath  Cam- 
brian sandstone,  the  northern 
edge  of  an  east-west  band  of  this 
rock  being  situated  about  1,000 
feet  southeast  of  the  Iron  Moun- 
tain shaft. 

SECTION  THIRTEEN  AND  VICINITY. 

By  A.  C.  Spencer. 

The  tract  of  640  acres  known 
as  H.  and  G.  N.  Section  Thir- 
teen lies  about  4 miles  south  of 
the  Iron  Mountain  property,  on 
the  southwest  side  of  San  Fer- 
nando Creek,  at  the  mouth  of 
Willow  Creek.  Magnetite  has 
been  found  at  several  places  on 
this  tract  and  at  several  locali- 
ties in  the  neighborhood  on  both 
sides  of  San  Fernando  Creek. 

The  distribution  of  these  show- 
ings is  indicated  on  the  accom- 
panying sketch  map  (fig.  13). 

There  has  been  some  prospect- 
ing south  of  the  east-west  road 
leading  to  Epperson's  house, 
about  2 miles  east  of  San  Fer- 
nando Creek,  and  east  of  Epper- 
son's boundary  line.  The  old  figure  12.— Distribution  of  magnetite 2 miles  east  of 
, i , i,  ’ j 1 Castell  (B,  fig.  10). 

trenches  are  so  badly  nlJed  that 

they  afford  no  indication  of  what  may  have  been  found,  and  all 
that  can  be  seen  at  present  is  rather  sparse  float  of  magnetite  in 
small  pieces.  This  float  may  be  found  at  intervals  for  about  400 
feet  along  a line  trending  a little  west  of  north. 

Three-quarters  of  a mile  southeast  of  Epperson's  house,  where  the 
road  crosses  a small  ravine,  heavy  float  of  magnetite  in  solid  chunks 
is  noted.  This  float  may  be  traced  to  a small  outcrop  near  by,  but 
74625°— Bull.  450—11 4 


50  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

nothing  may  be  said  of  the  prospects  of  this  occurrence  until  some 
development  work  has  been  done.  The  ore  closely  resembles  the 
material  on  the  surface  at  the  Iron  Mountain  mine. 

About  1J  miles  southwest  of  the  locality  mentioned  in  the  foregoing 
paragraph  and  half  a mile  south  of  the  Otto  house  chunks  of  solid 
magnetite  a pound  or  more  in  weight  were  noted  in  the  wash  of  a 
small  drain.  Though  hornblende  gneisses  outcrop  in  the  vicinity, 
the  ground  is  largely  covered  by  rock  waste,  so  that  no  suggestion 
is  warranted  as  to  where  this  ore  would  be  found  in  place.  East 
and  south  of  this  locality  granite  is  very  much  in  evidence,  though 
as  noted  in  the  description  of  the  Bader  tract,  slivers  of  gneiss  are 


included  in  the  area  northwest  of  the  Bader  workings.  Careful 
search  in  this  interval  of  2 miles  failed  to  reveal  any  iron-ore  float. 

West  of  San  Fernando,  in  section  13,  magnetite  has  been  discovered 
at  three  localities,  the  relative  positions  of  which  are  roughly  indi- 
cated on  the  sketch  map.  The  presence  of  float  ore  led  to  the  dig- 
ging of  several  pits,  some  of  which  are  still  in  such  condition  as  to 
show  that  the  magnetite  occurs  in  gneiss.  The  ore  and  the  country 
rock  are  distinctly  layered,  with  dips  toward  the  east.  A study  of 
the  southeasterly  pits  suggests  the  presence  of  at  least  two  leads 
somewhat  less  than  100  feet  apart,  trending  a few  points  east  of  north. 

Fairly  abundant  float  may  be  found  for  a distance  of  about  600 
feet  along  this  zone,  and  three  pits  have  been  dug.  On  the  south  an 
opening  8 feet  deep  has  exposed  1 foot  of  solid  ore  dipping  east  with 


IRON  ORES. 


51 


a granite  footwall.  At  a depth  of  3 feet  the  granite  cuts  off  the  ore 
along  a flat  contact. 

A hole  6 feet  deep  situated  somewhat  east  of  the  last-mentioned 
shows  7 feet  of  layered  material-carrying  ore.  The  strike  is  N.  10°  E. 
and  the  dip  about  25°  E.  The  lead  is  complex,  being  made  up  of  two 
fairly  solid  layers  of  ore  separated  by  light-colored  granitic  rock 
carrying  a minor  amount  of  magnetite.  The  upper  ore  layer  is 
from  10  to  14  inches  thick  and  the  lower  layer  about  2 feet  thick. 
The  immediate  footwall  is  whitish  granite  gneiss  about  1 foot  thick, 
and  below  this  is  hornblende  gneiss  carrying  considerable  magnetite. 
(See  fig.  14.)  A short  distance  east  of  this  pit  is  an  exposure  of 
hornblende  gneiss  carrying  garnet  and  epidote. 

The  next  opening  to  the  north  is  4 feet  deep.  Here  the  rock  layers 
exhibit  a low  dip  to  the  east.  At  the  bottom  is  hornblende  gneiss, 
then  a layer  of  white  gneiss  varying  from  1 foot  to  18  inches  in  thickness 
and  carrying  irregular  masses 
of  ore,  one  of  which  was  noted 
to  have  a diameter  of  1 0 inches ; 
next  above  this  layer  comes  8 
inches  of  hornblende  rock,  and 
this  is  followed  by  gneissoid 
granite.  Magnetite  is  dissem- 
inated through  the  hornblende 
rock  in  fine  grains,  but  in  the 
white  gneiss  the  iron  mineral 
is  coarsely  granular.  This  oc- 
currence strongly  suggests  that 
the  ore  was  generated  in  a 
layer  of  intrusive  material,  or,  more  definitely  stated,  the  impression 
is  given  that  this  ore  is  of  igneous  origin.  The  reader  will,  how- 
ever, note  that  the  general  features  of  the  Llano  ores  have  not  been 
interpreted  as  particularly  favoring  a hypothesis  of  igneous  origin. 

About  90  feet  west  of  the  4-foot  pit  a shallow  excavation  shows  a 
10-inch  layer  of  magnetite  embedded  in  white  gneiss.  This  ore  con- 
tains flakes  of  mica  and  closely  resembles  ore  from  the  Deep  Creek 
locality  described  on  a subsequent  page. 

The  surface  indications  just  south  of  Willow  Creek  forks  are  rather 
meager,  as  very  little  work  has  been  done. 

North  of  Willow  Creek,  on  the  top  of  the  hill,  is  a single  pit  9 feet 
deep  which  affords  a good  exposure  of  magnetite-bearing  gneiss.  The 
strike  of  the  layering  is  N.  35°  W.  and  the  average  dip  about  50°  NE. 
Approximately  8 feet  of  rock  is  exposed  and  about  half  its  bulk 
appears  to  be  magnetite.  The  casing  material  of  the  lead  is  mica- 
bearing granite  gneiss  of  the  same  general  appearance  as  that  at  the 
Iron  Mountain  mine.  The  general  character  of  the  ore  is  like  that 


Figure  14. — Relation  of  ore  layers  in  pit  south  of  Wil- 
low Creek  in  section  13.  1,  Feldspar-magnetite  gneiss; 
2,  ore;  3,  gneiss;  4,  magnetite;  5,  pegmatite;  6,  granite 
gneiss;  7,  hornblende  gneiss. 


52  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

taken  from  the  Bacler  incline,  but  the  rock  layers  exhibit  more  irregu- 
larity and  are  more  contorted  than  at  the  Bader  locality.  Layers  of 
solid  magnetite  are  in  no  place  more  than  8 inches  thick,  but  a 30-inch 
layer  of  rock  is  estimated  to  be  three-fourths  magnetite.  Most  of  the 
magnetite  is  fine  grained,  but  here  and  there  strings  and  bunches  of 
coarse-grained  mineral  are  noted.  As  represented  in  the  sketch 
giveii  as  figure  15,  the  immediate  hanging  wall  is  feldspathic  gneiss 
carrying  mica  and  magnetite;  the  footwall  is  light-hued  granitic 
rock  nearly  free  from  dark  minerals.  Immediately  under  the  con- 
torted layer  of  heavy  ore  represented  on  the  left  side  of  the  sketch  is 
a layer  of  granitic  material  with  ore  irregularly  distributed  through  it. 
This  portion  of  the  lead  presents  the  appearance  of  an  injection  which 
has  been  forced  into  the  ore-bearing  rock;  if  it  is  actually  invading 

material,  fragments  of  ore  tom 
from  the  walls  have  been  drawn 
out  and  incorporated  in  its 
mass. 

The  immediate  environs  of 
the  pit  exhibit  no  exposures, 
bedrock  being  covered  by  an 
apparently  deep  mantle  of  resid- 
ual sand.  Float  ore  is  not 
noted  along  the  strike  of  the 
lead. 

Though  there  is  some  doubt 
concerning  the  proper  classifica- 
tion of  the  rocks  with  which 
the  ore  in  section  13  is  asso- 
ciated, they  have  been  mapped 
as  belonging  to  the  lower  (fighter)  series  of  schists  (Valley  Spring 
gneiss).  Another  possibility  is  that  they  represent  the  dark  schists 
very  extensively  injected  by  granitic  material. 

West  of  section  13,  in  the  drainage  basin  of  the  north  fork  of  Willow 
Creek,  iron  ore  has  been  found  at  several  points,  and  here  the  rocks 
are  definitely  recognized  as  belonging  to  the  dark  series  (Packsaddle 
schist)  with  associated  limestones.  Aside  from  the  Olive  mine,  this 
is  the  only  occurrence  of  really  noteworthy  segregations  of  magnetite 
which  can  be  unequivocally  assigned  to  this  set  of  rocks. 

The  approximate  boundary  of  the  dark  schist  area  is  shown  on  the 
sketch  map  (fig.  13,  p.  50).  It  is  to  be  noted  that  the  principal  show- 
ings of  ore  are  aligned  parallel  to  this  boundary  as  it  is  represented 
upon  the  map.  The  ore  layers  dip  toward  the  interior  of  the  dark 
schist  area. 

Southeast  of  the  main  fork  of  North  Willow  Creek  ore  float  a few 
shallow  openings  show  the  presence  of  magnetite  at  various  points 
along  a curving  fine  about  5,000  feet  in  length  and  at  a few  isolated 


NE 


SW 


Figube  15. — Sketch  of  8-foot  ore  surface  in  magne- 
^ tite  gneiss. 


IRON  ORES. 


53 


points  north  and  east  of  this  line.  The  ore  material  exhibits  a some- 
what siliceous  aspect,  and  all  of  it  is  distinctly  layered.  Near  the 
main  creek  and  again  southeast  of  the  tributary  which  passes  the 
Taylor  house,  fragments  of  ore  lying  on  the  surface  are  made  up  of 
alternating  layers  of  dense,  fine-grained  magnetite  and  of  quartz,  the 
layers  varying  in  thickness  from  one-half  inch  to  2 inches.  It  seems 
that  there  are  at  least  two  distinct  layers  of  this  material  in  the 
northern  portion  of  the  range.  Their  maximum  thickness  appears  to 
be  less  than  2 feet. 

In  the  central  part  of  the  range  more  massive  ore  is  exposed,  and  at 
a pit  north  of  the  Taylor  house  a 17-foot  section  of  the  ore  is  exposed. 
The  ore  is  a mixture  of  magnetite  and  hornblende,  and  it  is  judged 
from  what  may  be  seen  on  the  surface  that  a layer  of  similar  material 
at  no  place  less  than  4 feet  thick  has  an  extent  along  the  strike  of 
about  600  feet.  Near  the  house  the  ore  mass  is  probably  more  than 
20  feet  wide. 

A sample  representing  the  entire  17  feet  of  ore  exposed  in  the  pit 
mentioned  above  gave  the  following  analysis: 


Analysis  of  iron  ore  from  sec.  13,  Llano  County , Tex. 
[R.  C.  Wells,  analyst,  U.  S.  Geol.  Survey.] 

Fe 

Si02 

Mn 

P 

S 

Ti02 


35.87 

34.57 

1.05 

.07 

.04 

.15 


From  the  surface  indications  it  is  believed  that  this  body  of  iron- 
bearing material  may  be  expected  to  hold  its  size  and  character  to  a 
depth  of  several  hundred  feet  along  the  dip.  Only  the  lean  nature  of 
the  material  stands  in  the  way  of  the  suggestion  that  the  lead  is 
worthy  of  detailed  exploration;  but  it  seems  hardly  likely  that  any 
but  high-grade  ores  will  warrant  the  railroad  construction  required 
for  transportation.  Enrichment  of  this  material  by  means  of  mag- 
netic concentrators  would  appear  to  be  feasible  from  the  technical 
standpoint,  but  at  present  certainly  not  practically  advisable. 

Three  or  four  minor  outcrops  of  magnetite  north  of  the  north  fork 
of  the  creek  appear  to  be  of  no  particular  interest.  They  exhibit  the 
same  general  trend  as  the  main  range,  but  it  is  not  possible  to  corre- 
late them  in  any  way  with  the  more  prominent  line  of  outcrops. 

From  the  structural  features  of  the  ore  range  which  has  been 
described  it  appears  to  be  obvious  that  the  ore  is  developed  along  a 
definite  horizon  in  a set  of  sedimentary  rocks;  any  additional  charac- 
teristics which  have  been  observed  as  bearing  on  the  origin  of  the  ores 
will  be  discussed  later  in  more  detail. 


54  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

RILEY  MOUNTAIN. 

By  A.  C.  Spencer. 

Prospecting  has  been  carried  on  at  several  places  along  the  east 
base  of  Riley  Mountain  between  Click  post  office  and  Honey  Creek, 
and  also  north  of  Honey  Creek.  (See  fig.  16.)  Most  of  the  surface 
showings  are  pyrite  gossans,  though  one,  situated  1 mile  north  of 
Click,  is  magnetite. 

The  pyrite  bodies  were 
under  exploration  during  the 
summer  of  1909,  so  that  a 
fair  opportunity  of  studying 
their  features  was  afforded. 

Development  work  on  the 
Roberts  place,  south  of  Honey 
Creek,  shows  that  the  iron  cap 
gives  place  to  the  original  sul- 
phide within  20  feet  of  the 
surface.  At  this  place  the 
sulphur-bearing  material  is 
arsenical  iron  pyrites.  The 
mass  has  been  shown  to  have 
a width  of  15  feet  and  has 
been  exposed  (June,  1909)  for 
a length  of  25  feet.  Adjacent 
to  the  Roberts  pit  (an  incline) 
float  may  be  traced  for  a dis- 
tance of  500  feet  along  the 
lower  slope  of  the  mountain; 
somewhat  farther  north  are 
other  showings  along  the  same 
general  trend.  The  deposit  is 
in  limestone  ad j acent  to  a very 
strong  fault  which  brings  the 

Figure  16.-Map  showing  location  of  pyrite  deposits  stratified  limestones  of  Riley 
north  of  Click  post  office  and  their  relations  to  faul  ts . . , 

Mountain  against  very  much 
older  crystalline  schists  on  the  east.  The  ore  is  not  on  the  fault  but 
about  50  feet  west  of  it.  It  appears  to  have  been  deposited  by  replace- 
ment of  the  limestone  and  to  follow  the  bedding  of  the  rock  which 
dips  toward  the  west  and  away  from  the  fault.  The  rocks  are  poorly 
exposed,  but  there  is  reason  for  believing  that  the  rocks  are  greatly 
broken  adjacent  to  the  main  line  of  faulting,  so  that  it  may  be  that 
the  ore  follows  a zone  of  shattering  rather  than  a layer  of  the  lime- 
stone. 

The  conditions  of  structure  suggest  that  the  deposits  should 
exhibit  considerable  continuity  in  depth,  but  developments  are  not 


IRON  ORES. 


55 


adequate  to  show  whether  or  not  such  is  the  case.  The  fault  adjacent 
to  which  the  pyrite  ore  occurs  is  traceable  for  several  miles  south- 
ward from  Honey  Creek,  though  evidences  of  iron  capping  were  not 
recognized  far  beyond  the  Roberts  opening. 

About  a mile  north  of  Honey  Creek,  on  the  Bedford  tract,  is  a shaft 
said  to  have  been  opened  prior  to  the  settlement  of  the  district. 
Near  by  a shaft  was  sunk  in  1909  to  a depth  of  70  feet.  Here  there  is 
evidently  a crush  zone  adjacent  to  a strong  fault.  The  lead  which  has 
been  opened  by  the  shaft  appears  to  be  a filling  of  crushed  material 
along  a fault  which  brings  together  cherty  limestone  on  the  west  and 
red  sandstone  on  the  east.  The  material  of  the  lead  is  red  iron  oxide 
and  coarsely  crystalline  calcite.  Brown  iron  ore  in  the  crystalline 
form  of  pyrite  (that  is  to  say,  limonite  pseudomorphs  after  pyrite) 
was  observed,  but  part  of  the  red  oxide  may  have  been  derived  from 
the  alteration  of  carbonate  of  iron.  East  of  the  shaft  there  is  a band 
of  red  sandstone  60  feet  wide,  then  another  fault  bringing  up  the 
crystalline  schists. 

It  is  evident  that  the  showings  of  iron  gossan  in  the  neighborhood 
of  Honey  Creek  can  have  no  value  as  a source  of  iron  ore.  Whether 
or  not  the  deposits  from  which  the  gossan  has  been  derived  will  ever 
be  worked  as  a source  of  sulphur  or  arsenic  can  not  be  foreseen. 
Parties  engaged  in  exploring  the  deposits  state  that  the  sulphide 
shows  no  valuable  quantities  of  gold  or  silver. 

West  of  Click  post  office  the  basal  sandstone  of  the  sedimentary 
series  of  Riley  Mountain  laps  over  the  ancient  crystalline  schists. 
The  line  between  the  sandstones  and  the  schists  trends  northeast 
and  finally  curves  out  toward  the  east  to  meet  the  fault  along  the 
east  face  of  Riley  Mountain.  Along  this  boundary,  about  H miles 
north  of  Click,  abundant  float  of  very  pure  magnetite  is  noted  in  a 
small  branch  west  of  the  Wilson  house.  This  float  is  readily  traced 
to  its  source  at  the  sandstone  overlap.  Part  of  the  loose  ore  has 
undoubtedly  been  derived  from  the  lowest  part  of  the  sandstone,  as 
fragments  of  magnetite  may  be  seen  in  this  rock.  Another  part  may 
have  been  derived  directly  from  ore  occurring  in  the  schist,  though 
the  position  of  a lead  has  not  been  discovered.  On  the  whole  it 
seems  probable  that  all  of  the  material  is  really  debris  from  the  sand- 
stone and  that  the  bedrock  deposit  does  not  come  to  the  present 
surface  because  it  is  capped  over  by  the  sandstone. 

A few  hundred  feet  southeast  of  the  point  where  the  sandstone 
containing  magnetite  fragments  is  exposed  there  is  a shaft  said  to 
have  been  opened  in  search  for  copper  ore.  Though  the  material 
taken  from  this  shaft  does  show  the  presence  of  copper  minerals, 
there  is  nothing  to  encourage  further  work. 


56  MINERAL*  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

ORIGIN  OF  THE  IRON  ORES. 

By  Sidney  Paige. 

POSSIBLE  HYPOTHESES. 

Three  possibilities  have  been  recognized  in  an  endeavor  to  arrive  at 
a definite  conclusion  concerning  the  origin  of  the  iron  ores  described 
in  this  report.  They  are  as  follows: 

1.  That  the  beds  represent  igneous  segregations  from  a granitic 
magma  and  owe  their  tabular  form  to  flowage  under  pressure;  that  is, 
they  represent  granitic  magmas  impressed  with  a foliate  structure. 

2.  That  the  ores  are  replacements  of  sedimentary  beds,  either  before 
or  during  metamorphism,  due  to  emanations  from  a granitic  magma. 

3.  That  the  ores  represent  metamorphosed  iron-bearing  sediments. 

Since  the  arguments  presented  to  substantiate  the  last  mode  of 

origin  will  necessarily  involve  arguments  against  the  first  and  second, 
a separate  treatment  of  those  hypotheses  is  not  necessary. 

A modification  of  the  third  hypothesis  would  recognize  the  possi- 
bility that  iron  had  been  introduced  into  unmetamorphosed  beds, 
which  were  subsequently  metamorphosed. 

The  writer  alone  is  responsible  for  the  views  here  set  forth  and 
realizes  the  difficulty  of  arriving  at  a definite  conclusion.  The  value  of 
various  classes  of  evidence  varies  with  the  problem  in  hand;  only  by  a 
careful  weighing  of  these  values  can  a legitimate  conclusion  be  reached; 
and  speculation,  unless  demanded,  should  be  relegated  to  its  proper 
place.  The  writer  will  endeavor  to  distinguish  between  considera- 
tions that  are  speculative  and  those  that  are  not. 

The  considerations  presented  will  fall  under  the  following  heads: 

(1)  The  general  distribution  of  iron  throughout  geologic  forma- 
tions and  the  character  of  the  accompanying  beds;  (2)  the  geologic 
relations  of  the  iron  ores;  (3)  the  characteristics  of  the  ores  having  a 
bearing  on  origin;  (4)  the  relations  of  the  igneous  rocks  of  the  region; 
(5)  the  chemical  factors  involved;  (6)  comparison  with  other  regions. 

GENERAL  DISTRIBUTION  OF  IRON  THROUGHOUT  GEOLOGIC  FORMATIONS 
AND  THE  CHARACTER  OF  THE  ACCOMPANYING  BEDS. 

The  Upper  Cambrian  sandstones  and  limy  sandstones  of  Llano 
County,  Tex.,  carry  disseminated  iron  oxides — hematite  and  limo- 
nite.  Locally  there  is  a fairly  high  content  of  iron  (though  not  from 
a commercial  standpoint)  and  the  iron-bearing  horizon  is  persistent. 
Within  this  series  are  also  beds  bearing  glauconite — hydrous  potas- 
sium-iron silicate. 

The  specular  hematite  ores  of  Virginia  and  other  Appalachian  States 
occur  in  rocks  of  Cambrian  age. 

In  the  lower  Silurian  of  central  Bohemia,  composed  of  quartzites 
associated  with  slates,  graywacke,  conglomerates,  diabases,  amyg- 


IRON  ORES. 


57 


daloids,  and  diabase  tuffs,  occur  hematite  and  carbonate  iron  ores, 
the  former  in  diabase  tuffs,  the  latter  in  quartzites  between  gray- 
wacke  a slates. 

The  Clinton  ores  of  the  Silurian  are  interbedded  with  clay  shales, 
sandstones,  and  impure  limestones. 

Iron  ore  accompanies  the  “Coal  Measures”  of  the  Carboniferous  on 
the  Continent,  in  England,  and  in  the  United  States. 

The  ores  of  the  northern  Alps,  (probably  Permian)  are  in  a so-called 
graywacke  zone. 

The  minette  ore  beds  of  the  Dogger  formation  are  found  in  the 
Jurassic  of  Alsace-Lorraine  in  beds  of  a limy  and  sandy  composition. 
Green  iron  silicates  are  noted. 

Iq  the  Eocene  of  Bavaria  oolitic  ores  occur.  Glauconite  and 
quartz  sand  are  noted. 

Finally,  deep-sea  investigations  have  proved  the  very  wide  dis- 
tribution of  highly  ferruginous  sediment. 

These  facts  point  at  once  to  two  conclusions — that  the  presence  of 
iron  ore  is  to  be  expected  in  the  sedimentary  record  of  all  periods, 
and  that  this  means  of  accumulation,  that  is,  sedimentation,  illustrates 
at  least  one  potent  factor  in  ore  segregation. 

The  nature  of  the  metamorphic  rocks  found  in  the  pre-Cambrian 
complex  leaves  little  room  for  belief  that  the  processes  of  sedimenta- 
tion during  pre-Cambrian  time  could  have  been  appreciably  different 
from  those  which  proceeded  during  the  more  easily  read  periods 
which  followed.  It  is  therefore  natural  that  bedded  iron  ores  derived 
from  primary  sedimentary  deposits  should  be  present  in  the  pre- 
Cambrian  complex. 

J.  J.  Sederliolm* * *  6 has  described  in  great  detail  the  manner  in  which 
granites  have  intruded  the  schist-gneiss  series  of  Finland,  and  a 
remarkable  similarity  may  be  noted  between  the  processes  at  work 
there  and  those  observed  in  the  Llano  region;  but  he  makes  no  note 
of  iron  ore.  It  seems  to  the  writer  that  this  absence  of  iron  is  more 
than  a mere  accident  which  might  be  explained  away  by  referring  to 
the  vagaries  of  granite  intrusions  (introducing  iron  in  one  locality 
and  not  in  another) . It  is  more  logical  to  believe  that  the  reason  for 
the  absence  of  iron  ores  in  the  above-cited  locality  lies  in  the  fact 
that  that  portion  of  the  schist-gneiss  series  which  is  there  (in  Finland) 
exposed  to  observation  represents  beds  barren  of  sedimentary  iron 
deposits. 

GEOLOGIC  RELATIONS  OF  THE  IRON  ORES. 

So  far  as  could  be  observed  the  iron  ores  are  an  integral  part  of 
the  Llano  series  and  exhibit  much  the  same  relationship  to  the  other 

o“  Sandstone-like  rocks  which  in  addition  to  the  quartz  and  feldspar  of  an,  arkose  contain  rounded  or 

angular  bits  of  other  rock.  Some  varieties  * * * composed  largely  of  feldspar  may  be  difficult  in  the 

hand  specimen  to  distinguish  from  some  felsite.” — Pirsson,  L.  V.,  Rocks  and  rock  minerals,  p.  326. 

& Om  Granit  och  Gneis:  Bull.  Comm.  g€ol.  Finlande  No.  23.  (English  summary.) 


58  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

members  as  do  the  limestones  and  the  graphite  schists.  They  are 
tabular  in  form,  can  be  traced  along  the  strike  where  not  covered  or 
interrupted  by  granite,  follow  all  the  convolutions  of  the  rocks  which 
inclose  them,  vary  in  thickness  and  in  iron  content  as  do  graphite- 
bearing strata  in  carbon,  and  locally  grade  into  the  surrounding 
country  rock  by  a gradual  decrease  of  iron.  They  are  layered  depos- 
its, even  in  the  locality  of  their  heaviest  development. 

No  locality  was  observed  where  the  beds  in  which  the  ore  occurs 
cut  across  neighboring  beds,  as  might  be  expected  in  the  case  of  intru- 
sive sheets,  nor  were  beds  observed  where  great  unexplained  irregu- 
larities of  iron  content  were  present;  a lean  bed  following  along  the 
strike  did  not  essentially  change  its  character,  at  least  not  more 
rapidly  than  would  be  found  in  a sedimentary  ore.  There  are,  ipter- 
bedded  with  the  iron  ores,  barren  or  lean  layers  composed  of  the  same 
minerals  as  the  ore  gangue. 

CHARACTERISTICS  OF  THE  ORES. 

The  ore-bearing  rocks  are  crystallized  granular  schists  or  gneisses 
which,  so  far  as  observed,  have  undergone  the  same  degree  of  meta- 
morphism as  the  remaining  beds  of  the  series.  The  ore  occurs  as 
more  or  less  concentrated  grains  of  magnetite  (or  hematite,  in  part), 
with  quartz  and  feldspar  and  a little  biotite.  (See  PI.  IV,  B,  p.  10.) 
The  magnetite  seems  to  have  crystallized  either  just  before  or  simul- 
taneously with  the  feldspar  and  the  quartz.  A microscopic  exami- 
nation of  a specimen  of  lean  ore  gave  as  its  result  plagioclase  feldspar, 
largely  albite,  magnetite,  and  quartz,  in  the  following  proportions: 
Quartz,  50  per  cent;  feldspar,  26  per  cent;  and  magnetite,  22  per 
cent.  This  is  roughly  equivalent  to  the  following  composition : 

Composition  of  lean  iron  ore , Llano  County , Tex. 


Silica 67 

Alumina 5 

Soda 3 


Magnetite 22 

The  wall  rock  of  the  ore  (which  is  but  a lean  portion  of  the  ore) 
showed  approximately  the  following  composition  by  microscopic 
analysis : 

Composition  of  wall  rock  of  iron  ore , Llano  County , Tex. 


Si02 71 

A1,03 12 

Na20,  K20,  CaO  (largely  Na20) 7 

Magnetite 5 

Biotite 3 


A partial  chemical  analysis  of  the  gangue  of  the  Bader  ore  gives 
the  following  result: 


IRON  ORES. 


59 


Analysis  of  lean  iron  ore  from  the  Bader  incline , Llano  County , Tex. 
[W.  T.  Schaller,  analyst,  U.  S.  Geol.  Survey.] 


Silica  (Si02) 57.31 

Alumina  (A1203)  a 10. 15 

Ferric  oxide  (Fe203)  6 26.  66 

Lime  (CaO) 1.  20 

Potassa  (K20) 16 

Soda  (Na20) 5.93 


C 101.  41 

The  same  analysis,  recalculated  to  100  without  iron  to  show  com- 
position of  the  remaining  material,  is  as  follows: 


Analysis  of  lean  iron  ore  from  Bader  incline  recalculated  without  iron. 


[W.  T.  Schaller,  analyst.] 

Si02 

ai203 

CaO 

K20 

Na20 


76.  66 
13.  57 
1.  60 
.21 
7.  93 


99.  97 

The  most  interesting  point  in  this  analysis  is  the  presence  of 
sodium  in  excess  of  potassium,  for  the  sediments  of  the  region  as  a 
whole,  including  some  of  the  iron  ores,  showed  the  latter  in  much 
greater  abundance.  This  point  will  be  discussed  later. 

The  relations  thus  far  pointed  out  indicate  more  or  less  strongly 
that  the  iron  was  present  in  the  rock  before  metamorphism,  for  it 
follows  the  convolutions  of  the  schists,  may  be  traced  long  distances, 
was  apparently  crystallized  before  or  at  the  same  time  as  the  accom- 
panying minerals,  and  occurs  in  much  the  same  relation  as  does 
graphite,  a mineral  without  much  doubt  developed  in  this  field  in 
sedimentary  material.  Light  is  also  thrown  on  the  presence  of  iron 
in  the  rock  before  metamorphism  by  an  occurrence  of  lean  ores 
northwest  of  Bodie  Peak,  where  the  banded  material  carrying  the  mag- 
netite has  suffered  brecciation  by  intrusion  of  granite.  A thorough 
intermixing  of  the  brecciated  fragments  and  the  intruding  rocks  has 
taken  place.  Locally  the  angular  outlines  of  the  broken  fragments 
are  very  evident,  but  passing  northward  the  fragments  appear 
stretched  and  lentil  shaped,  and  if  the  angular  material  had  not  been 
observed  one  might  be  at  a loss  to  account  for  the  lentil-like  streaks. 
A microscopic  examination  showed  an  interesting  distribution  of  the 
magnetite.  It  occurs  both  in  the  brecciated  fragments  and  also 
between  them,  whereas  the  concentration  was  much  less  between  the 


a Including  Ti02  and  P2O5,  etc.  The  Ti02  is  present  in  small  quantity,  probably  less  than  0.5  per  cent. 
b Total  iron,  that  is,  Fe0+Fe203- 

c Summation  high  on  account  of  reckoning  FeO  as  Fe203.  The  correction  to  be  deducted  from  the  total 
is  about  0.83  per  cent. 


60  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

fragments  than  in  them.  This  feature  may  indicate  a more  or  less 
mobile  state  of  the  iron,  due  to  the  injection  of  granitic  material. 
The  microscope  showed  a granular  mass  of  quartz  and  microcline 
feldspar  (the  latter  dominant)  and  magnetite,  with  certain  lens- 
shaped areas  where  the  magnetite  was  heavily  concentrated  (the 
mashed  fragments).  In  these  areas  quartz  was  almost  wholly  lack- 
ing, magnetite  and  feldspar  being  the  minerals  present.  The  writer 
believes  that  the  magnetite  found  between  the  fragments  was  derived 
from  the  fragments  of  the  intruded  sediments  and  not  from  the  intrud- 
ing magma. 

BEARING  OF  IGNEOUS  ROCKS  OF  THE  REGION  ON  ORIGIN  OF  IRON  ORE. 

The  basic  intrusive  rocks  described  above  have  no  genetic  relation, 
so  far  as  observed,  to  the  iron  ore  and  they  will  not  be  -discussed  in 
that  connection.  That  they  may  have  been  important,  however,  in 
effecting  chemical  changes  in  the  sediments  at  the  time  of  their 
intrusion  will  be  pointed  out  later.  The  granitic  rocks  of  the  region, 
on  the  other  hand,  are  intimately  associated  with  the  ores,  and  the 
< hypothesis  of  a genetic  connection  with  them  may  not  be  so  readily 
dismissed. 

As  has  been  indicated,  the  iron  ores  are  found  in  rocks  believed  to 
represent  a sedimentary  base  and  owe  their  origin  either  to  replace- 
ment of  metamorphosed  beds,  or  to  original  deposition  with  or 
secondary  introduction  into  unmetamorphosed  strata.  The  granite, 
wherever  found  in  association  with  iron  ores,  is  intrusive  into  them, 
cuts  across  the  bedding,  or  is  interleaved  with  the  ore  beds.  In  fact, 
it  presents  exactly  the  same  relations  to  the  iron  ore  that  it  presents 
in  numerous  places  to  the  mica,  the  graphite,  or  the  hornblende 
schist  series,  into  which  group  of  rocks  it  can  hardly  be  argued  that 
the  mica,  the  graphite,  and  the  hornblende  were  introduced  by  the 
granite.  In  the  case  of  the  ore-bearing  rocks,  however,  and  also  in 
the  case  of  certain  feldspathic  schists,  the  mineral  composition  of  the 
invading  and  the  invaded  rock  is  strikingly  similar.  The  writer 
believes  this  to  be  a fortuitous  condition,  for,  as  is  well  known,  certain 
metamorphosed  sediments  have  a composition  very  similar  to  that 
of  granite. 

A very  small  percentage  of  magnetite,  not  more  than  ordinary, 
occurs  in  the  granites  of  the  region.  In  the  pegmatites  there  are  a 
few  exceptions  and  in  one  instance  a notable  one.  Near  Gallihaw 
Crossing  a pegmatite  dike  several  feet  thick  was  observed  cutting 
across  the  schistosity  of  the  mica  schist  series.  It  was  composed  of 
feldspar,  magnetite,  garnet,  epidote,  and  limonite.  The  magnetite, 
which  was  abundant,  occurred  in  irregularly  shaped,  often  elongated 
masses  throughout  the  dike  and  apparently  crystallized  •simultane- 


IRON  ORES. 


61 


ously  with  the  feldspar,  though  this  is  not  certain.  Bedded  iron  ores 
may  exist  not  far  distant  from  the  locality,  as  small  outcrops  were 
seen.  The  dike  apparently  has  had  little  contact  effect  on  the  schists 
which  it  cuts.  It  is  suggested  that  it  may  have  acquired  its  magnetite 
in  passing  through  beds  of  iron  ore.  Where  pegmatites  occur  in  a 
region  of  abundant  amphibole  schist,  hornblende  was  noted  in  the 
pegmatite,  a fact  certainly  suggestive;  and  where  pegmatite  had  cut 
limestone,  scapolite  was  formed  in  the  dike,  clearly  exhibiting  the 
absorption  of  lime,  though  whether  from  the  immediate  vicinity  or 
elsewhere  is  not  certain. 

In  certain  localities,  where  the  effects  of  intrusion  and  impregnation 
have  been  most  intense,  abundant  magnetite  crystallized  with  feld- 
spar has  all  the  appearance  of  an  original  mineral  in  the  granite 
magma;  but  never  is  the  possibility  absent  that  an  iron-bearing 
sedimentary  base  has 
been  absorbed  by  the 
intruding  mass. 

It  is  evident  from 
what  has  just  been  said 
respecting  the  geologic 
relations  of  the  granite 
to  the  schists  that  if  the 
iron  is  a result  of  re- 
placement, by  means  of 
magmatic  emanations, 
some  granite,  other 
than  the  one  now  ob- 
served, was  involved  in 
the  process. 

It  is  hardly  conceiv- 
able that  a granite  presenting  such  indubitable  evidences  of  its 
intrusive  nature  could  have  been  the  principal  factor  in  the  intense 
metamorphism  observed,  which  is  believed  to  be  largely  the  effect  of 
dynamic  forces  other  than  intrusion.  The  metamorphism  was  com- 
plete, or  at  least  well  under  way,  before  the  injection  of  the  granite 
took  place. 

Though  this  statement  seems  to  the  writer  a reasonably  safe  con- 
clusion, it  should  be  said  that  phenomena  are  observed  locally  which 
might  be  used  as  an  argument  for  igneous  introduction  of  the  magne- 
tite; such,  for  example,  as  the  locality  shown  in  the  accompanying 
sketch  (fig.  17).  The  clear  evidence  of  crosscutting  should  here  be 
noted,  however,  and  the  possibility  of  original  iron  in  the  schist  kept 
in  mind.  On  the  north  side  of  Llano  River  a short  distance  west  of 
Hickory  Creek  the  granites  show  almost  completely  absorbed  schist 
fragments,  in  which  but  the  faintest  outline  of  the  original  fragment 
remains,  indicated  by  broadly  spaced  lines  of  magnetite.  (See  fig.  18.) 


7t  ' 


^Granite  id- 
/ ' <-x-V  I ' i7 ' 

,s  - \ i r i / N , O i n / ' 

/ ' ;K-  w -f ' 

- 7\  /-  i "■ 

Magnetite 

Figure  17. — Concentration  of  magnetite  along  edges  of  schist 
fragment  at  granite  contact. 


62  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

It  seems  more  probable  that  the  granite,  acting  on  an  iron-bearing 
base,  had  by  assimilation  rearranged  the  quartz  and  feldspar,  the  iron 
remaining  approximately  in  its  original  position,  than  that  the 
granite  had  introduced  this  iron  and  then  absorbed  the  schist. 

CHEMICAL  RELATIONS. 


With  the  schist-gneiss  group  considered  as  a metamorphosed  sedi- 
mentary series  and  the  intrusive  nature  of  the  granite  borne  in  mind, 
certain  facts  of  general  geologic  application  may  have  weight  in  arriv- 
ing at  a conclusion  regarding  the  nature  of  the  iron.  It  is  a recog- 
nized fact  in  geologic  science  that  the  important  result  of  regional 
metamorphism,  in  general,  is  a change  of  form  rather  than  a chemical 
addition  or  subtraction.  The  schists  of  Llano  County  might  well  be 
the  result  of  such  metamorphism  without  any  considerable  additions. 

They  are  generally  high  in  potassa 
and  silica,  two  elements  which 
Bastina  and  others  have  shown 
are  likely  to  be  dominant  in  meta- 
morphic  sediments.  Van  Hise6 
points  out  that  “ quartz  and  acid 
feldspars  have  very  nearly  the 
same  specific  gravity,  and  unless 
such  material  be  gradually  con- 
tributed to  the  water  so  that  it 
can  be  handled  by  strong  waves 
and  currents  for  a long  time  be- 
fore final  deposition  quartz  and 
acid  feldspar  will  not  be  sepa- 
rated” and  as  the  mica  is  carried 
away,  “consequently  in  the  com- 
paratively shallow  water  along  the  shore,  many  nearly  pure  quartz- 
feldspar  sands  may  be  built  up.”  Glauconite  also  is  a deposit 
restricted  largely  to  the  borders  of  the  continental  shelf.  He  also 
says:c  “From  * * * muds  carbonates  are  mainly  removed  in 

solution,  the  hydroxides  are  removed  to  some  extent,  and  the  highly 
oxidized  iron  largely  remains.”  In  regard  to  the  pelite  gneisses  he 
says  in  part:d  “While  the  greater  part  of  the  potassium  probably 
passes  into  muscovite,  where  the  potassa  is  abundant,  a portion  of 
it  passes  into  feldspar,  producing  orthoclase  and  microcline,  since 
these  minerals  are  rather  abundant  in  many  of  the  schist  pelites  and 
gneiss  pelites.” 


Granite 

Magnetite  grains  showing 
trace  of  old  schist  lines 


Figure  18.— Remhant  of  schist  fragment  in  granite 
mass.  Note  lines  of  magnetite. 


a Bastin,  E.  S.,  Chemical  composition  as  a criterion  in  identifying  metamorphosed  sediments:  Jour. 
Geology,  vol.  17,  No.  5,  1909. 

6Van  Hise,  C.  R.,  A treatise  on  metamorphism:  Mon.  U.  S.  Geol.  Survey,  vol.  47,  1904,  p.  873. 
cldem.  p.  889.  . 

dldem  p.  900. 


IRON  ORES. 


63 


Grubenmann  a also  points  out  that  “ there  occur  marly  sandstone  or 
argillaceous  marls,  whose  chemical  composition  approaches  so  nearly 
that  of  igneous  rocks  that  confusion  may  arise  in  their  discrimination.” 

The  analysis  of  the  wall  rock  at  the  Bader  incline  shows  soda  as 
dominant  over  potash.  This  relation  was  also  observed  at  the  Iron 
Mountain  ore  body.  Iron  ores  in  the  western  part  of  the  quadrangle, ' 
however,  are  associated  with  a decidedly  potassic  gangue,  as  indicated 
by  the  prevalence  of  microcline  feldspar.  As  normal  sediments  are  in 
great  part  or  entirely  of  the  potash  type,  an  explanation  should  be 
offered  for  the  high  soda  content  of  this  particular  sediment. 

As  described  earlier  in  this  report,  amphibolite  and  mica  schists 
form  a fairly  definite  unit  in  the  schist  series;  it  was  also  noted  that 
amphibolites  are  occasionally  found  within  the  lighter  schist  series, 
and  it  was  suggested  that  in  many  places  they  might  be  derived  from 
basic  sills  intrusive  into  the  sedimentary  series  prior  to  its  deep  burial 
and  foliation.  The  contact  metamorphism  produced  by  such  intru- 
sion into  clay  shales  has  been  studied  in  various  localities  throughout 
the  world  and  in  several  places,  at  least,  with  the  very  definite  and 
similar  result  of  finding  that  soda  and  silica  have  been  added  and  pot- 
ash removed,  but  in  the  cases  to  be  cited,  without  the  addition  of  iron. 

Though  it  cannot  be  proved  that  the  relations  about  to  be  presented 
existed  in  Llano  County,  they  are  given  as  a possible  if  not  a probable 
explanation  of  present  conditions;  at  the  same  time  it  is  assumed 
that  the  introduction  of  soda  took  place  prior  to  the  deep  burial  of  the 
rocks,  with  the  result  that  under,  conditions  of  intense  regional  meta- 
morphism and  accompanied  by  complete  recrystallization  of  the 
rocks  albite  was  formed  in  place  of  microcline  or  orthoclase. 

Teall,  in  British  Petrography,6  says: 

A striking  feature  [speaking  of  adinole,  a rock  produced  by  contact  metamorphism 
of  clay  shale  by  diabase  intrusion]  is  the  large  percentage  of  soda  which  the  rocks  con- 
tain. This  has  been  proved  by  Schenck  c to  be  due  to  an  actual  impregnation  of  the 
sediment  with  alkali  derived  from  the  eruptive  rock.  Thus  at  Bochtenbeck,  by 
Niedersfeld,  the  unaltered  rock  contains  1.16  per  cent  of  soda,  the  altered  rock  4.94, 
4.56,  and  3.59  per  cent;  at  Kuhlenberg,  by  Silbach,  the  unaltered  rock  contains  1.15, 
the  altered  rock  7.14  per  cent;  at  Silberberg,  the  unaltered  rock  contains  0.50,  the 
altered  rock  6.03  per  cent.  We  are  thus  led  to  the  important  conclusion  that  the  albite 
of  the  rocks  altered  by  diabase  is  largely  if  not  wholly  a secondary  product,  due  to  the  actual 
impregnation  of  the  surrounding  sediment  by  material  derived  from  the  eruptive  rock. 

Rosenbusch,d  in  describing  the  contact  effect  of  diabase  sills  on 
clay  shale,  says: 

These  products  of  the  innermost  parts  of  the  diabase  contact  areas  are  called  adinole 
and  are  composed  of  an  extremely  fine-grained  mixture  of  allotriomorphic  albite  and 
quartz,  with  which  are  very  sparingly  associated  actinolite,  epidote,  rutile  or  anatase 
or  even  titanite. 

The  chief  difference  between  this  and  the  deep-seated  contact  zone  lies  in  the 
complete  chemical  changes  of  the  schists. 


a Grubenmann,  U.,  Die  Kristallinen  Schiefer,  1904,  p.  12. 
b Teall,  J.  J.  H.,  British  petrography,  1888,  p.  220. 
c Die  Diabase  des  oberen  Ruhrthals:  Inaug.  Diss.  Bonn,  1884. 
d Rosenbusch,  H.,  Elemente  der  Gesteinslehre,  2d  ed.,  1901,  pp.  340-347. 


64  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


Analyses  la-lc  and  2a-2c  and  4a-4c  show  different  stages  of  change  with  increasing 
distance  from  the  diabase. 

One  sees  that  the  oxides  RO  and  K20  strongly  decrease,  while,  on  the  other  hand, 
Si02  and  Na20  considerably  increase — that  is  to  say,  silica  and  soda  are  added  in 
appreciable  amounts  to  the  schist  substance. 


la. 

lb. 

lc. 

2a. 

2b. 

2c. 

4a. 

4b. 

4c. 

Si02 

69. 27 

73.74 

75.25 

54.02 

55.06 

72.63 

60.28 

57. 77 

74. 16 

Ti02 

.92 

.37 

A I2O3 

13. 12 

14. 81 

11.80 

21.22 

19.75 

15.81 

22!  61 

19.35 

11.85 

F 62O3 

.62 

.02 

Trace. 

2.51 

1.83 

2. 53 

1.29 

.82 

FeO 

5.24 

1.31 

1.76 

6. 48 

7.55 

.74 

.45 

3.37 

1.66 

MnO 

.09 

. 11 

1.74 

Trace. 

Trace. 

.06 

MgO 

1.36 

1.29 

1.57 

3.01 

2.21 

1.21 

1.35 

4.35 

2. 10 

CaO 

.12 

.61 

.32 

1.64 

3.59 

1.02 

,13 

1.71 

2.10 

Na20. 

2.25 

5.47 

7.54 

3. 36 

7.51 

8.33 

.54 

8.22 

6.57 

K20 

4.31 

1.51 

.61 

3. 71 

.84 

.75 

5.73 

.22 

.15 

h2o 

3. 36 

.70 

.81 

1.97 

1.83 

.61 

3. 62 

2. 34 

.52 

co2  .. 

.04 

.09 

FeS2... 

.62 

.84 

.49 

.03 

.04 

.08 

Organic  substance 

Trace. 

Trace. 

Trace. 

Trace. 

.97 

.18 

Specific  gravity 

100. 40 
2. 653 

100. 41 
2. 658 

100. 15 
2. 653 

99.66 

2.678 

100. 17 
2.813 

101. 10 
2.778 

99.57 

99.76 

100.76 

J.  Morgan  Clements  ° has  well  shown  the  metamorphism  produced 
in  sediments  by  the  intrusion  of  diabase  dikes  and  sills.  The  changes 
resulting  in  a clay  slate  due  to  this  influence  are  indicated  in  the 
following  analyses.  Clements  was  not  able,  because  of  poor  exposures, 
to  select  his  specimens  with  absolute  certainty  as  to  their  exact 
distance  from  the  diabase.  He  says: 

From  previous  determinations  in  other  regions  it  is  well  known  that  the  adinoles 
are  next  to  the  contact,  while  the  spilosites  (and  desmosites)  are  intermediate  between 
them  and  the  clay  slates.  The  following  series  of  analyses  are  arranged  in  the  order 
of  approach  to  the  dolerite,  as  determined  by  the  character  of  the  rocks: 


Analyses  of  rocks  from  Lake  Superior  iron  region. 

1. 

2. 

3. 

4. 

Si02 

60.28 

52. 51 

57.77 

74.16 

Ti02 

.69 

1.70 

.92 

.37 

Al2Ch 

22. 61 

19.00 

19.35 

11.85 

None. 

None. 

Fe2C>3 

2. 53 

3.31 

1.29 

.82 

FeO 

. 45 

7. 19 

3.37 

1.66 

MnO 

Trace. 

Trace. 

Trace. 

.06 

CaO 

.13 

1.55 

1.71 

2. 10 

BaO 

.04 

Trace. 

None. 

None. 

SrO 

Trace. 

Trace. 

MgO 

1.35 

3.29 

4.35 

2. 10 

K20 

5. 73 

.70 

.22 

.15 

Na20 

.54 

6. 72 

8.22 

6.57 

Li20 

Trace. 

None. 

H20  at  100°- 

.60 

b .34 

b .18 

.05 

H20  at  100°+ 

3.62 

c 3.26 

c 2. 34 

.52 

P2Oi 

.03 

.15 

.04 

.08 

C02 

None. 

None. 

None. 

.09 

S and  S O3 

None. 

None. 

C 

.97 

.18 

Cl 

None. 

None. 

F 

Trace. 

None. 

99.57 

99.72 

99. 76 

100. 76 

a A contribution  to  the  study  of  contact  metamorphism:  Am.  Jour.  Sci.,  4th  ser.,  voi.  7,  pp.  81-91. 
»>  H20  at  110°. 
c H20  above  110°. 


1.  Clay  slate,  specimen  No.  32497,  U.  S.  Geol.  Survey.  Analyst,  George  Steiger. 

2.  Spilosite,  specimen  No.  32861,  U.  S.  Geol.  Survey.  Analyst,  H.  N.  Stokes. 

3.  Spilosite,  specimen  No.  32827,  U.  S.  Geol.  Survey.  Analyst,  H.  N.  Stokes. 

4.  Adinole,  specimen  No.  32465,  U.  S.  Geol.  Survey.  Analyst,  George  Steiger. 


IRON  ORES. 


65 


In  these  analyses  the  usual  increase  of  silica  as  the  dolerite  is  approached  is  at  once 
noticeable,  and  hand  in  hand  with  it  goes  the  diminution  in  percentage  of  alumina 
and  iron  oxides.  The  content  of  water  and  carbonaceous a matter  also  suffers  dimi- 
nution, as  was  to  be  expected. 

The  most  noteworthy  difference  between  the  clay  slate  and  the  contact  rocks  is 
shown  in  the  relations  of  potash  and  soda.  This  is  well  brought  out  in  an  examination 
of  analyses  Nos.  1 and  2.  It  will  be  seen  that  there  is  only  about  one-eighth  as  much 
potash  in  the  contact  rocks  as  in  the  normal  clay  slate;  while,  on  the  contrary,  about 
12  times  as  much  soda  as  there  was  in  the  slate  has  been  added  to  the  contact  rock. 
This  causes  a reversal  of  the  relations  of  the  soda  and  potash,  so  that,  whereas  in  the 
clay  slate  there  is  present  10  times  as  much  potash  as  soda,  we  find  in  the  contact  rock 
taken  as  an  example  very  nearly  10  times  as  much  soda  as  potash . * * * 

The  very  considerable  changes  which  are  shown  by  the  above  analyses  to  have 
taken  place  in  the  metamorphism  of  the  slates,  especially  the  changes  in  the  amount  of 
silica  and  soda  resulting  in  the  production  of  albite  in  large  quantity,  seem  to  add 
weight  to  the  supposition  that  in  such  contacts  an  actual  transfer  of  material,  possibly 
in  the  form,  as  has  been  suggested  by  others,  of  the  soda- silicate,  does  take  place  from 
the  basic  igneous  rock  to  the  intruded  slate. 

In  summing  up,  then,  it  may  be  said  that  the  light-colored  schist 
series  as  a whole  are  eminently  quartzose  potassic  rocks;  that  it  is 
important  to  recognize  the  fact  that  introduction  of  material  in  the 
deep-seated  zone,  except  on  a very  minor  scale,  is  not  necessary  to 
account  for  their  chemical  composition ; and  that  the  introduction  of 
soda  may  have  taken  place  at  the  intrusion  of  the  diabase-like  rocks 
prior  to  deep-seated  conditions. 

Attention  should  here  be  called  to  the  potassic  composition  of  the 
lean  ores  in  the  extreme  western  part  of  the  area  and  to  the  possi- 
bility of  their  derivation  from  glauconitic  sediments.  That  glauco- 
nite is  capable  of  altering  to  magnetite  can  not  be  questioned.  J.  K. 
Prother  6 says,  in  describing  the  glauconite  from  the  greensands  of 
New  Jersey:  “ In  some  glauconite  grains  are  rows  of  small  grains  of 
magnetite.  All  gradations  are  noted  from  unaltered  glauconite  to 
glauconite  changed  to  a network  of  magnetite — magnetite  is  seen 
fdling  the  cracks  of  glauconite.” 

It  is  reasonable  to  suppose  that  such  a process  may  have  operated 
in  the  case  of  the  ores  under  discussion. 

It  would  seem  extremely  probable  that  if  the  siliceous  glauconite 
beds  of  the  Cap  Mountain  formation,  for  example,  were  subjected  to 
metamorphic  conditions,  potassic  feldspars,  quartz,  and  magnetite 
would  result. 

PROBABLE  CONDITIONS  AT  TIME  OF  INTRUSION. 

In  attempting  to  state  the  reactions  taking  place  at  contacts  of 
igneous  masses  with  sedimentary  rocks  at  great  depths,  one  is  forced 
to  base  conclusions  on  phenomena  only  imperfectly  understood.  It 


a The  carbon  in  Nos.  2 and  3 was  not  determined. 
b Jour.  Geology,  vol.  13,  p.  511. 

74625°— Bull.  450—11 5 


66  MINERAL  RESOURCES  OE  LLANO-BURNET  REGION,  TEXAS. 

is  all  the  more  important,  then,  to  refrain  from  speculation  and  to 
confine  oneself  to  reasonable  analogies. 

If  we  make  the  assumption  for  a moment  that  gaseous  solutions 
capable  of  carrying  iron  into  the  schists  were  present  at  the  time  of 
intrusion,  an  examination  of  the  conditions  probably  obtaining  in  the 
wall  rock  at  that  time  do  not  give  much  if  any  support  to  the  idea  that 
such  replacement  would  have  taken  place. 

Field  evidence  shows  that  the  schists  were  in  large  part  in  the  zone 
of  flowage,  where  openings  in  the  rocks,  if  existing  at  all,  were  sub- 
capillary, producing  practically  impervious  strata.  The  crystalline 
interlocking  of  the  iron  with  its  accompanying  minerals  indicates 
that  the  iron  was  present  at  the  time  of  crystallization,  which  pre- 
ceded the  intrusion  of  the  granite.  Many  crystalline  limestones  were 
observed  which  showed  no  evidence  of  replacement,  and  where  lime- 
stone has  been  converted  into  wollastonite,  as  is  the  case  in  the  lower 
(lighter)  schist  series  (Valley  Spring  gneiss),  it  is  not  certain  that  the 
effect  was  not  due  to  thermal  metamorphism  of  impure  limestone. 
In  this  case  C02  was  expelled.  Barrell  a holds  that — 

Carbonic  acid  is  only  expelled  when  the  siliceous  impurities  of  the  limestone  are 
sufficient  to  combine  with  the  lime  set  free,  forming  lime  silicates.  This  ability  of 
deeply  buried  b limestones  to  retain  their  carbonic  acid  when  intensely  heated,  if 
free  from  other  impurities,  has  been  noted  by  a number  of  observers. 

A consideration  of  the  chemical  nature  of  the  remaining  beds  other 
than  limestone  places  them  in  a class  even  more  chemically  inactive 
than  the  limestone,  so  far  as  replacement  is  concerned ; for  they  are 
siliceous  rocks,  and  as  such  notably  inactive  except  where  pore  space 
(including  fractures)  exists. 

The  study  of  rock  magmas  has  shown  the  probability  that  when 
molten  they  exist  as  silicate  solutions  (various  silicates  in  mutual 
solution) ; further,  that  as  crystallization  ensues,  the  remaining 
magma  becomes  progressively  more  siliceous.  In  such  a system 
pegmatites  become  end  products  of  crystallization.  Harkerc  regards 
a rock  magma  as — 

A definite  mixture  of  silicate  compounds,  the  only  free  oxides  present,  at  least  in  a 
magma  approaching  the  point  of  crystallization,  being  those  parts,  if  any,  of  the  silica, 
alumina,  ferric  oxide,  and  water,  which  after  crystallization  appear  as  quartz,  corun- 
dum, hematite,  and  free  water. 

Moreover,1 d he  regards  mineralizing  substances  such  as  water, 
chloride,  fluoride,  etc.,  as  “ an  integral  part  of  the  rock  magma  itself/’ 
and  considers  them  “ operative  throughout  the  whole  progress  of 
consolidation  of  the  magma.  * * * The  pegmatites  e themselves 

represent  the  watery  residual  magma,  except  that  the  greater  part 

a Barrell,  Joseph:  Am.  Jour.  Sci.,  4th  ser.,  vol.  13  p.  279. 
b Italics  by  present  writer. 

c Harker,  A.  H.,  The  natural  history  of  rocks,  p.  166. 
dldem,  p.  288. 
e Idem,  p.  295- 


IRON  ORES.  67 

of  the  water  and  other  volatile  substances  was  expelled  in  the  final 
crystallization.” 

At  this  stage  of  consolidation  should  exist  the  most  perfect  oppor- 
tunity for  a liquid  substance  to  permeate  the  rocks;  but  this  has  not 
taken  place  except  in  a mechanical  way  by  interleaving  or  crosscutting, 
though  these  processes  have  locally  proceeded  in  a most  intricate 
manner.  It  is  probable  that  the  water  and  the  silica  of  the  final  product 
are  represented  in  the  quartz  veins,  which  are  very  numerous  in  this 
region;  but  this  mode  of  entrance  into  the  schist  shows  clearly  that 
the  easiest  avenues  were  chosen,  namely,  fractures  and  cleavage 
planes. 

With  the  completion  of  crystallization  in  a rock  magma a the  contained  water  and 
other  volatile  substances  * * * must  be  disengaged.  We  must  suppose  a certain 
leakage  by  diffusion  into  and  through  the  contiguous  country  rocks;  but  it  is  probable 
that  this  escape  is  not  important  until  the  temperature  has  fallen  considerably. 

High  temperature, & which  in  liquids  diminishes  viscosity  and  so  promotes  diffusion, 
has  the  opposite  effect  in  gases;  and  in  view  of  all  the  conditions  it  is  likely  that  a 
large  part  of  the  volatile  constituents  is  in  general  retained  down  to  a late  stage . N e ver- 
theless,  more  or  less  of  the  water  and  other  gases  must  pass  into  the  neighboring  rocks 
while  these  are  still  heated  by  the  intrusion. 

Such  transition,  it  is  believed,  can  occur  only  where  pores  or  frac- 
tures exist,  or  where  pressure  is  so  slight  as  to  permit  the  ready  expul- 
sion of  C02  (in  the  case  of  limestones)  to  admit  the  entrance  of  solu- 
tions, or  where  chemical  interchange  is  possible.  It  is  extremely 
doubtful  if  solutions  capable  of  producing  magnetite,  quartz,  and 
albite  can  permeate  a nearly  impervious  siliceous  formation  for  any 
great  distance.  Assuming  that  they  have  done  so  in  this  region,  they 
could  not  do  more  than  progressively  fill  the  minute  cavities  found ; 
for  it  is  known  that  silicate  rocks  are  those  which  offer  the  greatest 
resistance  to  attack,  and  the  relation  of  the  iron  minerals  in  the 
schists  is  of  the  same  nature  as  that  of  the  albite  and  the  quartz  which 
accompany  it. 

The  local  abundance  of  magnetite  in  the  pegmatite  might  be 
advanced  as  an  argument  for  the  igneous  introduction  of  the  iron  into 
the  schists ; if,  however,  a quantitative  analysis  were  possible  over  a 
broad  area  the  writer  believes  it  probable  that  the  iron  ratio  to 
pegmatite  would  be  shown  to  be  much  the  same  as  is  the  iron  ratio 
in  the  granites  to  the  parent  magma.  The  extreme  fluidity  of  the 
pegmatite  material  should  offer  favorable  opportunities  for  such 
segregations  of  iron  minerals  as  are  found,  without  postulating  any 
great  quantity  of  iron  when  compared  with  that  found  in  the  body 
of  the  schists. 

The  ratio  of  phosphorus  to  iron  in  the  Llano  ores  is  interesting. 
Practically  all  the  analyses  at  hand  show  a very  low  content  of 


a Ilarker,  A.  H.,  op.-cit.,  p.  299. 


b Idem,  p.  303. 


68  MINERAL.  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

phosphorus;  that  is,  Bessemer  grade.  An  examination  of  sedi- 
mentary ores  the  world  over  shows,  for  the  most  part,  phosphorus 
in  greater  quantities  than  Bessemer  practice  permits.  It  would 
seem  necessary,  therefore,  if  these  ores  are  to  be  assigned  to  a sedi- 
mentary origin,  to  offer  some  explanation  of  this  divergence.  It 
should  be  pointed  out  that  the  Bessemer  limit,  as  a point  on  a scale 
of  phosphorus  content,  is  a low  point,  and  that  its  delicacy  being 
considered,  this  limit  might  easily  have  been  disturbed  by  condi- 
tions not  understood  and  now  hidden  by  the  metamorphism  which 
has  taken  place. 

Van  Hise  a gives  as  the  result  of  an  anatysis  of  78  shales  an  average 
content  of  0.17  per  cent  phosphorus;  of  624  sandstones,  0.07  per  cent. 
The  Llano  ores  may  well  have  been  deposited  with  arkosic  sandstone. 
It  must  be  admitted,  however,  that  the  presence  of  the  iron  in  sedi- 
mentary deposits  seems  to  involve  the  presence  of  phosphorus  and 
that  therefore  this  comparison  loses  some  of  its  value. 

It  is  credibly  reported  that  certain  stock  piles  in  the  Lake  Superior 
region  originally  above  Bessemer  grade  have  by  processes  of  weather- 
ing been  leached  of  sufficient  phosphorus  to  render  them  of  Bessemer 
grade. 

It  is  possible,  then,  that  in  the  case  of  the  Llano  ores,  first,  that 
only  a small  percentage  of  phosphorus  was  deposited  with  the  ore;  or, 
second,  that  by  some  process  of  leaching  phosphorus  was  removed; 
or,  third,  that  unknown  reactions  due  to  metamorphism  have  served 
to  remove  or  lower  the  phosphorus  content. 

It  should  be  said  also  that  those  magnetite  deposits  of  the  Adiron- 
dacks  to  which  an  igneous  origin  has  been  ascribed  by  careful  work- 
ers contain  from  0.01  to  2 or  3 per  cent  of  phosphorus;  but  this 
fact,  though  it  could  be  legitimately  used  as  an  argument  against 
igneous  origin,  does  not  alter  any  value  the  low  content  of  phos- 
phorus may  have  as  an  argument  against  sedimentary  origin. 

COMPARISON  WITH  OTHER  REGIONS. 

Beck, 6 in  describing  the  iron  ores  of  Krivoi-Rog,  in  southern  Russia, 
says : 

These  ore  deposits,0  ordinarily  grouped  as  those  of  the  Saxagan  basin,  lie  on  the 
Inguletz,  a western  tributary  with  north-south  course  entering  into  the  Dnieper 
River  above  Cherson.  They  are  of  exceedingly  great  importance  to  Russia,  because 
they  lie  close  to  the  Donetz  coal  basin  extending  east  of  the  Dnieper.  The  ores  occur 
in  a strongly  folded  crystalline  schist  striking  north-south,  whose  geologic  age  is  as 
yet  uncertain.  In  its  upper  part  this  rock  consists  of  carbonaceous  slate  with  but 

a Van  Hise,  C.  R.,  A treatise  on  metamorphism:  Mon.  U.  S.  Geol.  Survey,  vol.  47, 1904,  p.  975. 

ft  Beck,  R.,  The  nature  of  ore  deposits  (tr.  by  W.  H.  Weed),  p.  75. 

c See  reviews  of  the  works  of  Kontkiewitsch,  Piatnitzky,  Domherr,  Monkowsky,  Karpinsky,  and  others 
in  Zeitschr.  prakt.  Geologie,  1896,  p.  271;  1897,  pp.  182,  186,  278,  374;  1898,  p.  139  (Macco).  See  also  Strip- 
pelmann,  L.,  Siid-Russlands  Magneteisenstein  und  Eisenglanzlagerstatten  in  den  Gouvemements  Jeka- 
terinoslaw  und  Cherson,  1873;  and  Cordeweener,  J.,  Geologie  de  Krivoi-Rog  et  de  Kertsch,  Paris  1902. 


IKON  ORES. 


69 


few  layers  of  ore;  next  below  come  the  ore-bearing  quartzite  schists,  underlain  by 
clay  slate,  actinolite  schist,  quartz  chlorite  schist,  talc  schists,  arkose,  and  itacolumite, 
like  mica  schists,  and  finally  by  gneiss  (probably  dynamometamorphic  granites) 
and  true  granites.  The  ore-bearing  strata  form  a long-extended  fold,  and  show  a close 
minor  plication  by  which  quartzite  beds  have,  according  to  Macco,  changed  into  a 
succession  of  quartzite  nodulss,  like  conglomerate  cobbles  in  a clay  slate.  In  the 
double  row  of  deposits  extending  parallel  to  the  Saxagan  River  the  two  most  important 
ore  bodies  are  those  near  Krivoi-Rog;  the  lower  one  about  98  feet  (30  meters)  and  the 
uppermost  about  262  feet  (80  meters)  thick.  The  ores  consist  of  magnetite,  for  the 
most  part  altered  to  red  hematite,  with  45  to  70  per  cent  of  iron  and  0.01  to  0.02  per 
cent  P205.  The  very  irregular  ore  masses  lie  in  a finely  banded  yellowish  white ? 
red,  or  brown  ferruginous  quartz  schist  whose  crystalline  quartz  grains  inclose  numer- 
ous magnetite  particles. 

Newland,®  referring  to  nontitaniferous  iron  ores  in  the  Grenville 
series  of  the  Adirondacks,  says : 

There  can  be  no  doubt  that  the  form  assumed  by  the  ore  bodies  is  conditioned  by 
the  structures  of  the  inclosing  rocks.  * * * This  feature  is  least  apparent  in  the 
gneisses  of  the  igneous  series,  and  most  evident  in  the  banded  gneisses  and  schists 
of  the  Grenville.  The  ores  consequently  must  have  been  deposited  before  the  great 
regional  disturbances  took  place,  or  at  least  before  the  rocks  received  their  present 
structural  arrangement. 

Though  Newland  found  it  difficult  or  impossible  to  determine  the 
origin  of  some  of  the  iron-ore  deposits  in  the  Adirondack  region,  he 
regarded  the  origin  of  others  as  quite  obvious.  For  example,  describ- 
ing the  deposits  near  Crown  Point,  on  Lake  Champlain,6  he  says: 

The  magnetites  * * * are  associated  with  banded  gneisses  and  schists  that 
can  be  classed  without  reserve  in  the  sedimentary  or  Grenville  series.  They  have 
a simple  tabular  or  lenticular  form,  swelling  and  narrowing  to  some  extent  along  the 
strike  and  dip,  but  otherwise  are  little  disturbed.  * * * The  Grenville  rocks 
which  occur  near  the  ores  are  mostly  hornblende  and  biotite  quartzose  gneisses  with 
occasional  intercalations  of  thin-bedded  schists.  They  are  conspicuously  foliated 
and  variable  in  their  composition  from  layer  to  layer.  * * * The  Grenville  has 
been  broken  up  into  patches  and  larger  irregular  areas  by  granite  which  has  invaded 
the  series  from  below.  * * * The  granite  frequently  cuts  across  the  stratification 
of  the  sediments  and  sends  off  dikes  and  stringers  which  penetrate  the  latter  in  all 
directions. 

Other  instances  might  be  cited  where  field  relations  point  to  the 
conclusion  that  metamorphosed  sediments  are  the  base  of  the  iron- 
ore  formation  and  that  metamorphism  has  in  all  probability  pre- 
ceded granitic  invasion,  but  the  localities  mentioned  are  sufficient 
for  the  purpose. 

SUMMARY. 

In  conclusion  it  may  be  said,  as  Van  IIisec  has  so  well  pointed 
out  in  referring  to  the  distribution  of  the  elements — 

that  a general  result  of  metamorphism  and  accompanying  processes  is  that  many  of 
the  secondary  rocks  are  depleted  in  reference  to  each  metal  and  that  correlative  with 


a Newland,  D.  H.,  Geology  of  the  Adirondack  magnetic  iron  ores:  New  York  State  Mus.  Bull.  119, 1908, 
p.  27. 

b Newland,  D.  H.,  op.  cit.,  pp.  40-41. 

c Van  Hise,  C.  R.,  A treatise  on  metamorphism:  Mon.  U.  S.  Geol.  Survey,  vol.  47,  1904,  p.  1035. 


70  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

such  depletion  other  deposits  are  formed  in  which  each  metal  is  segregated.  Since 
these  processes  result  in  deposits  in  which  each  of  the  common  metals  is  segregated, 
why  should  we  hold  that  the  metal  of  a present  deposit  of  gold  or  silver  or  copper 
[or  iron] « is  derived  solely  from  an  immediately  adjacent  igneous  rock  unless  evidence 
for  this  be  conclusive.  The  natural  view  is  that  the  metallic  ore  deposits  of  the 
world  are  broadly  accumulated  results  of  the  processes  of  segregation  carried  on 
throughout  geological  time. 

The  geologic  events  probably  involved  in  the  formation  of  the 
Llano  ores  may  be  indicated  as  follows: 

1.  Deposition  of  iron  as  oxide,  carbonate,  etc.,6  with  the  sediments, 
either  in  extended  basins  or  along  borders  of  the  sea. 

2.  Burial  and  intrusion  of  dikes  and  sills  of  a diabasic  type  with 
possible  local  introduction  of  soda.  Possibly  granitic  intrusions. 

3.  Deep  burial  with  following  folding  and  metamorphism,  and 
second  intrusion  of  basic  types. 

4.  Intrusion  by  granite  magma  with  great  local  disruption. 

5.  Elevation  above  sea,  and  exposure  by  erosion. 

GOLD. 

Small  quantities  of  gold  may  be  found  at  many  localities  through- 
out the  pre-Cambrian  area.  It  must  be  said,  however,  that  in  general 
the  quantity  is  so  small  as  to  be  valueless  from  the  standpoint  of  a 
mining  enterprise.  Results  of  many  assays  made  of  specimens  said 
to  contain  gold  were  decidedly  discouraging.  The  following  table 
shows  the  results  of  a number  of  assays : 


Results  of  assay  for  gold  and  silver,  Llano  County,  Tex.a 


Gold, 
per  ton. 

Silver, 
ounce 
per  ton. 

Locality. 

1 

Trace. 

Trace. 

Sulphides  from  Mr.  Sheeon’s  place,  4 miles  south  of  Llano. 

Graphitic  schist  2|  miles  southwest  of  Niggerhead  Mountain,  three-fourths  of  a 
mile  east  of  the  Colorado  (flowing  south)  and  a scant  half  mile  north  of  the  river 
(flowing  east). 

2 

None. 

None. 

3 

Trace. 

.56 

Thomas  Prospect,  Hooking  Hollow. 

4 

None. 

None. 

Shaft  near  Gallihaw  Crossing.  Pegmatite  dike. 

5 

None. 

None. 

2\  miles  east  by  north  from  Granite  Knob  and  one-fourth  mile  south  of  the  east 
and  west  road,  near  edge  of  sheet.  Gossan  from  vein. 

6 

Trace. 

.38 

4 miles  west  of  Burnet  and  north  of  Spring  Creek,  Bailey  Prospect. 

7 

$0.  31 

None. 

Quartzite-like  rock  near  Parkinson’s  quarries,  110  feet  long,  30  feet  wide. 

8 

. 10 

None. 

Iron  oxide  If  miles  east-northeast  of  Field  ( reek  village. 

9 

. 10 

None. 

Edwards’s  pasture,  near  east  boimdary  2-foot  vein,  240  feet  long  (by  float).  Pros- 
pect holes  5 miles  east  by  south  of  Valley  Springs. 

10 

None. 

None. 

Southeast  of  No.  9 and  west  of  Pecan  Creek,  north  of  road  to  Edwards’s  ranch. 
Bedded  layer  in  graphite  schist. 

Willow  Creek  above  Bumet-V alley  Springs  road;  outcrop  about  2\  miles  west 
of  Valley  Springs. 

11 

. 10 

None. 

12 

. 10 

None. 

Heavy  pyrite  gossan  in  graphite  schist  on  knoll  1J  miles  west  by  south  of  Miller 
Mountain. 

a Assays  1-6  by  E.  E.  Burlingame  Denver,  Colo.  Assays  7-12  by  Ledoux  & Co.  New  York  City. 


On  Henry  H.  Sheeon’s  place,  about  4 miles  south  of  Llano,  a shaft 
has  been  sunk  to  prospect  pyrite  veins  in  the  quartzite  schist.  The 


a Inserted  by  present  writer. 

b The  chemistry  of  the  possible  manner  of  original  deposition  need  not  be  discussed  here,  as  little  or  no 
evidence  is  at  hand  for  discrimination. 


GOLD. 


71 


pyrite  nearly  or  quite  accords  with  the  bedding  of  the  schists  which  at 
this  point  dip  steeply  to  the  southeast.  The  iron  mineral  is  accom- 
panied by  much  quartz  in  narrow  veins  swelling  and  pinching  in  the 
layers  of  the  schist.  Apparently  the  two  were  introduced  together. 
An  assay  of  this  pyrite,  which  is  very  abundant,  judging  from  the 
dump  (the  shaft,  unfortunately,  was  not  open  at  the  time  of  the  visit) , 
shows  no  gold.® 

The  only  prospect  visited  where  gold  was  present  in  sufficient  quan- 
tity to  warrant  further  prospecting  is  called  the  Heath  mine.  This 
prospect  is  located  5 miles  northeast  of  Llano,  just  north  of  the  Llano- 
Lone  Grove  road.  At  the  present  time  the  property  is  controlled  by 
Mr.  McCarty  Moore,  of  Dallas,  Tex.,  though  during  the  past  25  years 
a number  of  persons  have  been  interested  in  the  prospect. 

The  rocks  in  this  vicinity  are  a part  of  the  dark  (Packsaddle)  schist 
series.  Graphite  and  mica  schist  and  limestone  are  present.  At 
the  prospect,  intrusive  granite,  which  to  the  south  and  east  occurs  in 
large  masses,  has  broken  the  regularity  of  the  beds,  and  strikes  and 
dips  with  quite  variable  angles  may  be  observed.  Much  quartz  and 
pegmatite  have  interleaved  and  cut  the  schist  beds,  and  pyrite  is 
locally  present.  It  is  with  the  quartz  stringers  that  the  gold  seems 
to  be  largely  associated. 

In  the  subsoil  and  in  the  partly  decayed  schists  below,  where  ex- 
posed in  crosscuts,  a canary-yellow  efflorescence  or  stain  may  be 
noted  coating  quartz  stringers  and  distributed  in  spots  through  the 
decayed  rock.  This  stain  has  been  mistaken  occasionally  for  an 
oxidation  product  of  gold  tellurides.  An  examination  by  W.  T. 
Schaller  of  the  United  States  Geological  Survey  proves  the  material 
to  be  a compound  of  bismuth  and  vanadium.  The  only  known 
mineral  compound  of  bismuth  and  vanadium  is  the  mineral  pucherite, 
which,  however,  is  always  found  in  crystal  form.  The  yellow  com- 
pound has  been  noted  by  Mr.  Schaller  in  California  where  he  collected 
sufficient  material  for  an  analysis,  results  of  which  will  be  published 
at  a later  date. 

The  prospect  is  located  on  a low  spur  rising  to  the  north.  A cover 
of  residual  red  and  brown  soil  effectually  conceals  the  underlying 
decayed  schists  and  granites.  This  residual  soil  carries  gold,  un- 
doubtedly concentrated  by  the  removal  of  soluble  and  easily  trans- 
ported constituents  of  the  rock.  Values  are  also  reported  in  the 
underlying  schists. 

Figure  19  is  a sketch  map  on  which  are  shown  the  positions  of  some 
of  the  open  cuts  and  shafts  by  which  the  property  has  been  pros- 
pected. The  map  also  shows  the  general  northwest  trend  of  the 
schists  and  the  variable  dips  and  strikes  that  may  be  observed. 

In  1900-1901  a shaft  615  feet  deep  was  sunk.  Gold  is  reported 
from  this  shaft,  but  little  definite  information  could  be  obtained  as  to 


a See  table  on  page  70,  assay  1. 


72  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

its  value  or  the  depth  at  which  it  occurred.  The  writer  was  informed 
that  an  8-foot  band  of  black  schist  carried  fair  value  in  gold  associated 
with  molybdenite. 

The  material  on  the -dump  shows  that  the  lower  portion  of  the 
shaft  penetrated  feldspar-mica  schist  and  fine-grained  pink  intrusive 
granite. 

At  points  5 and  6 shown  on  the  sketch  map  two  50-foot  shafts  have 
been  sunk  and  connected  by  a drift.  The  results  of  any  systematic 
sampling  of  these  openings  are  not  at  hand.  High  values  are  not 
reported.  At  point  7 shown  on  the  sketch  map  two  shafts  45  feet 
deep  are  sunk  in  schist  and  intrusive  granite.  An  open  cut  foljnwing 
a quartz  vein  is  also  located  at  this  point.  The  presence  of  pyrite 
with  the  quartz  and  in  the  granite  is  noteworthy.  Open  cuts  are 
located  also,  as  indicated  at  1,  2,  3,  and  4,  and  a shaft  is  sunk  as  indi- 
cated at  11. 


X 


& B." 


3/  /: 


or 


X Dip  and  strike 
o Shaft 
■ House 
o Small  shaft 
/Trench 

x Fragments  of  float 


.5»v, 


-9  * 


>v 


500  Feet 

— i 


Figure  19.— Prospect  pits  and  shafts  at  Heath  gold  prospect. 


It  has  been  pointed  out  that  a foot  or  more  of  residual  soil  covers 
most  of  the  bedrock  in  this  vicinity.  This  soil  has  been  sampled  by 
60  shallow  pits  in  addition  to  the  open  cuts  shown  on  the  sketch  map. 
A sample  selected  with  great  care  by  the  writer  from  one  of  these  pits 
gave  an  assay  of  20  cents  in  gold. 

An  incline  has  been  run  from  the  surface  crosscut  shown  at  1 on  the 
sketch  map  (fig.  19)  southward  down  the  dip  of  the  schists  for  about  90 
feet.  A sample  from  the  west  wall  of  this  incline,  about  30  feet  from  its 
upper  end,  was  cut  from  the  grass  roots  down  to  the  bottom  of  the  cut, 
a distance  of  9 feet.  The  sample  was  crushed  on  a canvas  sheet,  mixed 
and  quartered  twice,  and  assayed  for  gold  and  silver,  and  $1.60  in 
gold  was  reported  by  the  assayer.0  A second  sample  from  the  east 
wall  and  12  feet  farther  down  the  incline  was  cut  from  6J  feet  of 
material.  The  top  of  this  cut  was  7 feet  below  the  grass  roots.  The 
sample  was  quartered  once  and  assayed  for  gold  and  silver,  and  20 


a Assays  made  for  the  U.  S.  Geol.  Survey  by  E.  E.  Burlingame,  of  Denver,  Colo. 


COPPEK. 


73 


cents  in  gold  was  reported.  A third  sample  was  taken  from  the  west 
wall  42  feet  down  the  incline  from  second  sample.  This  sample  cov- 
ered 4J  feet  of  material  and  was  5 feet  from  the  face  of  the  incline. 
It  was  quartered  once  and  assayed.  No  values  were  reported. 

A sample  was  taken  from  crosscut  3 (see  sketch  map)  on  its  south 
side.  It  included  6 feet  of  schist  and  a little  granite.  It  was  quar- 
tered once  and  assayed.  No  values  were  reported. 

Crosscut  2 (see  sketch  map)  was  sampled  at  three  points  about  75 
feet  apart,  two  on  its  northwest  side  and  one  on  its  southeast  side 
near  the  northeast  end.  The  three  samples,  covering  in  all  about  10 
feet  of  vertical  material,  weathered  schist  and  soil,  were  mixed  together 
and  quartered  once  and  assayed.  No  values  were  reported. 

A sample  was  taken  from  the  top  of  26  ore  sacks  and  from  an  ore 
pile  representing  picked  ore  selected  by  panning  tests.  This 
sample  assayed  $20.59  a ton  in  gold  and  silver,  of  which  19  cents 
was  silver. 

The  company  has  had  many  assays  made  of  material  from  the 
surface  and  from  the  cuts  and  the  incline.  Separate  assays  of  quartz 
from  veins  have  also  been  made.  In  all  these  instances,  values 
higher  than  those  found  by  the  writer  are  reported.  In  some  instances 
single  stringers  of  quartz  are  reported  to  carry  exceptionally  high 
values.  The  sample  from  the  ore  sacks,  noted  above,  was  of  very 
quartzose  material. 

It  seems  very  probable  that  in  large  measure  the  values  are  con- 
fined to  the  quartz  veins;  these  are  abundant  locally,  but  are  not 
persistent  and  are  not  of  such  size  that  they  could  be  worked  indi- 
vidually. 

Except  in  the  residual  material,  in  which  there  has  been  opportunity 
for  enrichment  by  the  removal  of  soluble  constituents  of  the  rock 
during  its  decay,  it  is  doubtful  if  sufficiently  high  values  in  gold 
could  be  relied  on  to  insure  profitable  mining.  This  point,  however, 
can  be  determined  only  by  assaying  many  carefully  taken  average 
samples. 

COPPER. 

No  encouragement  can  be  given  that  any  copper  prospect  visited 
during  the  course  of  the  investigation  on  which  this  report  is  based 
can  ever  be  of  commercial  value. 

About  one-half  mile  northwest  of  Wilberns  Glen  on  both  sides  of 
the  road  some  crosscuts  and  a shaft  about  35  feet  deep  have  been 
opened.  Films  of  malachite  were  noted  associated  with  epidotized 
and  garnet ized  schist. 

About  three-fourths  of  a mile  beyond  the  western  edge  of  the 
Llano  quadrangle  and  about  400  feet  south  of  the  Mason  road  pros- 
pecting has  been  done  on  what  is  known  as  the  Bauer  prospect.  At 


74  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

this  point  schists  striking  east  and  west  are  near  the  edge  of  a large 
mass  of  fine-grained  granite.  A shaft  (slope)  of  unknown  depth 
dips  50° S.  Carbonates  are  noted  over  about  150  feet  of  prospected 
ground.  No  sulphides  were  seen  on  the  dump.  A little  garnet  was 
noted.  Two  oarloads  of  ore  are  reported  to  have  been  shipped. 

In  May’s  pasture,  2 miles  south  of  Babyhead  and  a short  distance 
east  of  the  Llano-Babyhead  road,  a fine-grained  pink  granite  is 
seen  carrying  malaohite  and  some  azurite.  About  two  tons  of  3 per 
cent  rock  is  at  the  surface.  A small  trench  has  been  made. 

There  has  been  prospecting  for  copper  on  Adolf  Schneider’s  place, 
14  miles  north  of  Llano  River,  and  5 miles  east  of  the  Mason  County 
line,  on  a stream  joining  the  Llano  above  Bauer’s  ford.  Three  holes 
from  15  to  30  feet  deep  have  been  sunk  in  schists  which  strike  north 
and  dip  about  35°  E.  A little  chalcopyrite  associated  with  black 
garnet,  epidote,  quartz,  and  a little  calcite  may  be  seen  in  a layer 
of  schist.  Carbonates  extend  down  only  a few  feet,  and  but  little 
gossan  is  seen.  The  occurrence  is  on  the  west  side  of  a tongue  of 
fine-grained  red  granite  which  crops  about  30  feet  down  the  dip  to 
the  east. 

Chalcopyrite  and  a little  chalcocite  were  seen  in  the  intrusive 
granite  as  well  as  in  the  schists,  and  a microscopic  examination 
showed  clearly  its  secondary  nature — that  is,  it  in  part  fills  the  cracks 
in  feldspars.  The  solutions  therefore  which  brought  in  the  copper 
penetrated  the  rocks  later  than  the  intrusion  of  the  granite  and  took 
advantage  of  existing  fractures. 

An  assay  of  a sample  representing  about  200  pounds  of  ore  selected 
by  Mr.  Schneider  gave  the  following  result:  Gold,  $0.41  per  ton; 
silver,  trace;  copper,  0.94  per  cent. 

About  2 miles  east  of  Magill  Mountain  and  a short  distance  east  of 
Pecan  Creek,  prospecting  for  copper  has  been  carried  on.  Several 
shafts  and  crosscuts  have  been  opened.  At  this  point  the  pre- 
Cambrian  schist  series  is  cut  by  a network  of  pegmatite  and  quartz 
veins,  the  latter  often  paralleling  the  lamination  of  the  flat-lying 
schist.  The  schist  and  the  pegmatite  also  contain  disseminated 
pyrite,  chalcopyrite  and  bornite,  with  malachite  and  azurite.  The 
prospects  do  not  indicate  a deposit  of  value. 

In  the  town  of  Llano  and  in  the  near  vicinity  several  pits  have 
-been  sunk  in  the  hope  of  developing  a copper  property,  but  nothing 
was  seen  which  would  invite  further  work. 

Other  prospect  pits  were  seen  at  various  localities,  but  in  no 
instance  were  any  of  the  showings  of  such  a nature  as  to  warrant 
further  prospecting. 


MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS.  75 


LEAD. 

About  3 1 miles  north  of  Bluffton,  Burnet  County,  on  Silver  Creek, 
a tributary  of  Beaver  Creek,  a small  area  of  coarse  pink  granite  pro- 
trudes beneath  the  Cambrian  strata,  and  around  the  edges  of  this  out- 
crop galena  may  be  observed  in  the  limy  glauconitic  quartz  sandstone, 
which  here  rests  by  overlap  on  the  granite.  About  1J  miles  north  by 
west  of  this  locality  a similar  occurrence  is  found  on  Beaver  Creek, 
where  again  galena  occurs  in  glauconitic  sandstone  near  the  base  of 
the  sandstone  series  and  just  below  an  outcrop  of  pre-Cambrian 
granite  (on  the  creek).  The  locations  of  Beaver  and  Silver  Creeks  are 
shown  on  the  map  (fig.  20),  and  the  geologic  relations  at  the  Silver 


98°2o' 


Figure  20. — Map  showing  location  of  lead  prospects  north  of  Bluffton  and  area 
(A)  covered  by  figure  21. 

Creek  locality  are  shown  in  figure  21.  It  may  be  seen  from  these 
figures  that  at  this  point  overlap  occurs,  because  of  the  unevenness  of 
the  pre-Cambrian  floor  on  which  the  sediments  were  deposited.  It 
will  be  noted  also  that  quaquaversal  dips  occur  along  the  borders  of 
the  granite  mass.  In  the  field  small  faults  accompanied  by  zones  of 
slipping  and  brecciation  were  developed  along  this  unconformity. 
These,  with  the  steep  dips  (confined  entirely  to  the  contact),  plainly 
indicate  an  upward  movement  of  this  granite  mass,  a movement  of 
sufficient  magnitude  to  flex  the  beds  sharply,  but  not  sufficient  to  do 
more  than  break  them  slightly.  The  structure  at  the  locality  on 
Beaver  Creek  is  of  the  same  type,  though  in  that  locality  the  folding 
of  the  beds  due  to  a sharp  uplift  is  even  more  beautifully  shown 
(PI.  Y,  A). 


76  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

The  lead  occurs  apparently  as  a replacement  of  the  limy  sandstone, 
though  it  is  not  confined  to  that  member,  being  found  also  locally  in 
the  limestone.  It  can  not  be  said  to  follow  the  bedding  consistently, 
though  locally  it  may  do  so.  It  is  found  both  near  the  granite  floor 
and  also  a considerable  distance,  40  feet  or  more,  above  it.  A 
microscopic  examination  shows  that  the  galena  is  most  likely  a 
replacement  of  the  calcite  which  binds  together  the  quartz  and 
glauconite  grains  making  up  the  sandstone. 

Two  shafts  and  a tunnel  have  been  opened  on  the  property.  Only 

the  tunnel  was  in  condition  to 
be  examined.  From  the  65- 
foot  shaft  two  or  three  veins  of 
lead  are  reported  by  Dr.  Os- 
borne, who  owns  the  property. 
Sixteen  feet  from  the  top  of  this 
shaft  a vein  reported  3|  feet 
thick  is  said  to  run  75  ounces 
in  silver  and  20  per  cent  lead. 

Some  of  the  galena  from  this 
locality  was  examined  for  its 
silver  content.0  The  method 
used,  with  the  quantity  of  sam- 
ple submitted,  would  not  detect 
less  than  8 ounces  of  silver  per 
ton.  No  silver  was  detected.6 

The  tunnel  is  located  a short 
distance  south  of  Silver  Creek 
on  the  western  contact.  It  is 
run  S.  68°  W.  in  glauconitic 
sandstone.  Thirty  feet  in,  a 
o i Mile  crosscut  is  driven  7 feet  north- 

Figure  21.— Plan  and  ideal  section  showing  relations  West  and  18  feet  southeast.  A 
of  Upper  Cambrian  to  underlying  pre-Cambrian  ^ed  Qf  sandstone  about  18 
granite  at  lead  prospects  north  of  Bluffton.  a,  Ellen-  _ . . 

burger  limestone;  b,  Wilberns  formation;  c,  Cap  inches  thick  IS  here  Seen  dipping 
Mountain  formation;  d,  pre-Cambrian  granite.  23°  ? and  shows  dig _ 

seminated  galena.  At  the  end  of  the  crosscuts  and  also  at  a point 
near  the  tunnel  the  drift  has  been  widened,  evidently  for  the  purpose 
of  following  a body  of  ore  which  gave  out.  The  tunnel  was  con- 
tinued beyond  the  drift,  but  is  reported  to  have  struck  no  lead. 

The  origin  of  an  ore  deposit  generally  has  an  important  bearing  on 
a decision  regarding  the  probabilities  of  developing  a commercial 
deposit.  The  following  suggestions  are  offered  as  an  explanation  of 
the  occurrence  described,  but  the  writer  does  not  thereby  wish  to 

a w.  B.  Phillips  (Eng.  and  Min.  Jour.,  vol.  77, 1904,  p.  364)  reports  the  lead-bearing  strata  on  Silver  Creek 
to  be  6 to  12  feet  thick.  Assays  show  between  10  and  20  per  cent  lead  with  no  silver  or  gold. 
b Munroe,  Hall  & Hopkins,  chemists,  assayers,  engineers,  Washington,  D.  C. 


U.  S.  GEOLOGICAL  SURVEY 


BULLETIN  450  PLATE  V 


A.  FOLDING  OF  UPPER  CAMBRIAN  SANDSTONE  ON  BEAVER  CREEK,  NEAR  LEAD  PROSPECT. 

See  page  75. 


B.  PEGMATITE  AND  GRANITE  INTRUDING  SCHIST. 
See  page  1 0. 


GRAPHITE. 


77 


create  an  optimistic  sentiment  regarding  these  ores;  it  can  not  be 
said  that  the  prospects  which  were  available  for  study  would  warrant 
such  a view. 

It  is  significant  that  in  both  the  localities  described  the  lead  is 
concentrated  in  an  area  of  local  disturbance,  where  a dome-like  uplift 
has  to  some  extent  brecciated  the  rocks  and  caused  small  faults  to 
ippear.  It  is  noteworthy  also  that  the  pre-Cambrian  basement  at 
this  point  is  about  100  to  150  feet  higher  than  the  pre-Cambrian 
floor  to  the  west.  Seventy  to  90  feet  above  the  glauconite  horizon 
occurs  a shale  member  of  sufficient  thickness  to  act  as  a fairly  imper- 
vious cover.  Waters  carrying  lead  in  solution  circulating  under 
artesian  conditions  might  flow  upward  along  the  unconformity, 
reach  this  locality  of  relatively  open  space,  and  deposit  lead  sulphide. 
The  chemical  reaction  which  caused  this  precipitation  must  remain 
conjectural.  If  the  deposition  be  due  to  any  inherent  quality  of  the 
inclosing  rock,  one  would  suspect  that  the  presence  of  glauconite 
might  have  played  a part. 

It  is  interesting  to  note  that  this  galena  occurs  in  a series  which  is 
lithologically  very  similar  to  the  Lamotte  sandstone  and  the  dolomitic 
Bonneterre  limestone  of  southwestern  Missouri,  where  workable  ore 
bodies  are  found  both  in  that  sandstone  and  in  the  limestone  above. 
If  these  Texas  occurrences  are  of  a similar  type  to  those  of  south- 
western Missouri,  much  irregularity  may  be  expected  in  their  distribu- 
tion. Though  many  faults  occur  in  the  Texas  region,  some  of  con- 
siderable throw,  they  have  no  apparent  connection  with  the  galena 
other  than  the  local  effect  due  to  the  formation  of  open  space  by  the 
brecciation  described  above.  Considering  their  proximity  to  the  basal 
unconformity  and  the  presence  of  the  shales  above,  it  is  suggested 
that  the  deposits  owe  their  origin  to  lead-bearing  solutions  more  or 
less  controlled  by  the  relatively  impervious  pre-Cambrian  floor  below 
and  the  relatively  impervious  shale  above,  moving  laterally  in  past 
time  under  artesian  conditions,  the  lead  in  solution  having  been 
derived  by  leaching  from  many  feet  of  higher  strata  perhaps  many 
miles  distant  from  the  present  deposit. 

GRAPHITE. 

As  the  series  of  pre-Cambrian  rocks  described  above  were  in  part 
originally  shales,  sandstones,  and  limestones,  they  are  now  repre- 
sented by  schists  of  varying  composition.  Moreover,  certain  con- 
stituents have  become,  through  metamorphism,  of  possible  economic 
importance.  Such  an  instance  is  the  change  of  carbonaceous  matter 
originally  in  the  shales  to  graphite. 

Graphite-bearing  schists  are  widely  distributed  throughout  the 
pre-Cambrian  rocks,  though  the  content  of  graphite  is  variable.  In 
most  places  the  graphite  schists  are  associated  with  limestone  or 


78  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

marble,  a natural  occurrence,  for  carbonaceous  shales  are  often  asso- 
ciated with  limestone  strata.  Many  of  these  schists  can  be  traced  for 
long  distances. 

Graphite-bearing  schists  were  noted  at  many  localities,  but  since 
only  one  of  these  is  as  yet  considered  of  importance,  a description  of 
the  occurrence  at  this  locality  will  serve  as  a measure  of  those  left 
undescribed ; for  it  may  be  said  in  general  that  it  would  not  be  advis- 
able to  spend  money  on  prospecting  or  testing  at  other  localities  until 
the  deposit  in  question  is  proved  a commercial  success.  If  any  excep- 
tion be  made  to  this  statement,  it  would  be  that  perhaps  certain  beds 
carry  sufficient  graphite  to  be  of  value  as  a source  of  paint  pigment, 
in  the  industrial  manufacture  of  which  a very  impure  graphite  can  be 
used,  as  not  more  than  35  or  40  per  cent  of  graphite  is  required  in  the 
paint  pigment,  the  remainder  being  generally  siliceous,  aluminous, 
or  ferruginous  material.® 

The  locality  which  has  received  and  warranted  the  most  attention 
is  located  lj  miles  due  south  of  Lone  Grove,  is  approximately  1,500 
feet  west  of  Little  Llano  River  and  800  feet  north  of  the  Houston 
& Texas  Central  Railroad. 

The  graphite  occurs  in  graphitic  schists  of  the  upper  or  black  series 
which  in  this  vicinity  contains  considerable  limestone.  (See  map, 
PI.  Ill,  in  pocket.)  Granite  and  pegmatite  intrusion  has  locally  dis- 
rupted the  beds  to  a greater  extent  than  can  be  expressed  on  a map 
of  the  scale  here  published. 

The  graphite-bearing  schists  can  be  traced  with  interruptions  for 
one-half  mile  northwestward  from  a point  a little  west  of  the  railroad 
bridge,  through  the  present  workings,  to  a point  where  the  series 
disappears  beneath  overlying  Cambrian  sandstones.  Graphite  is 
also  reported  across  the  river  in  the  same  trend. 

The  deposit  has  been  prospected  by  a shaft  with  underground 
workings  and  by  a number  of  surface  cuts,  four  or  more  in  a distance 
of  about  500  feet.  Two  to  the  southeast  of  the  shaft  (about  150  and 
300  feet  from  it,  respectively)  only  show  granite  debris.  One  to  the 
north  of  it  about  150  feet  is  badly  filled.  A 70-foot  cut  about  25 
feet  north  of  the  shaft  gives  an  excellent  exposure. 

At  the  west  end  of  the  cut,  a mixture  of  schist  and  pegmatite  with 
cal  cite  veinlets  is  exposed  for  22  feet.  There  is  a little  graphite  in 
the  schist.  Limestone  is  exposed  in  the  extreme  west  end.  Next  to 
this  22  feet  of  lean  material,  an  irregular  mass  is  exposed,  about  3 
feet  across  and  extending  from  the  bottom  to  the  top  of  the  cut.  It 
contains  considerable  graphite,  mixed  with  quartz,  feldspar,  and  cal- 
cite  and  represents  a rich  graphite-bearing  layer  intruded  and  broken 
by  pegmatite  with  subsequent  filling  of  fractures  by  calcite. 


a Bastin,  E.  S.,  Graphite:  Mineral  Resources  U.  S.  for  1908,  pt.  2,  U.  S.  Geol.  Survey,  1909,  p.  720. 


GRAPHITE. 


79 


At  a first  glance  the  impression  might  be  formed  that  pegmatite 
had  introduced  the  graphite.  A careful  examination  of  the  graphite 
bunches  in  the  pegmatite  shows,  however,  that  they  represent  broken 
fragments  of  schist.  A specimen  was  polished  and  etched  with  hydro- 
chloric acid,  which  by  dissolving  out  the  calcite  contained  between 
the  laminae  of  the  schist  fragments  showed  clearly  the  schistose  nature 
of  the  graphite. 

Following  this  mass  is  6J  feet  of  fine-grained  mica  schist,  carrying 
a small  content  of  graphite,  after  which  is  exposed  6 feet  of  material 
similar  to  the  3-foot  irregular  mass  described  above.  Seven  feet  of 
schist,  practically  barren  of  graphite,  is  followed  by  25  feet  of  mate- 
rial similar  to  the  irregular  mass  of  graphite,  feldspar,  and  quartz, 


Figure  22.— Plan  of  workings  at  graphite  property  near  Lone  Grove. 


but  containing  more  of  the  latter  material  as  the  end  of  the  cut  is 
approached.  Decayed  granite  appears  in  the  east  end  of  the  cut. 

The  underground  workings  were  not  open  at  the  time  of  the 
writer’s  visit. 

An  average  sample  taken  over  the  length  of  the  cut  described  above 
showed  a carbon  content  of  11.45  per  cent’. 

The  locations  of  the  shaft,  cut,  and  underground  workings  are . 
shown  in  figure  22.  The  first  level  is  55  feet  below  the  collar  of  the 
shaft,  the  second  28  feet  below  the  first.  In  addition  to  the  workings 
shown  in  this  figure  is  an  exposure  of  some  5 feet  of  graphitic  mate- 
rial in  a small  pit  about  150  feet  northwest  of  the  shaft,  and  about 
300  feet  northwest  of  the  shaft  is  a long  crosscut  10  or  12  feet  deep 
in  greatly  decomposed  schist  and  gneiss,  practically  barren. 

A private  report  made  in  1902  by  William  Young  Westervelt  and 
furnished  by  the  courtesy  of  Mr.  R.  H.  Downman  contains  many 


80  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

interesting  data  on  this  property,  and  the  following  notes  are  ab- 
stracted from  it: 

The  only  point  at  which  sufficient  development  work  has  been  done  to  actually 
place  “ore  in  sight”  is  at  the  shaft  and  associated  workings,  represented  by  the  accom- 
panying plate. 

The  shaft,  for  the  first  5 feet,  is  built  up  through  the  dump,  but  with  this  exception 
is  entirely  in  a mass  of  graphite  ore  from  its  collar  to  the  first  leveL  There  being 
neither  timbers  nor  ladderway  in  the  shaft,  except  at  the  collar  and  levels,  it  was 
impracticable  to  take  a sample  of  it.  Careful  samples  of  the  levels  and  of  the  sump 
being  secured,  however,  sampling  of  the  shaft  was  not  deemed  necessary.  On  the  first 
level,  a drift  runs  northwest  on  a seam  of  graphitic  shale  about  5 feet  wide,  which  is 
proved  to  exist  for  about  30  feet  northwest  of  the  shaft  center  and  continues  beyond. 
Sample  No.  8 of  this  seam  assays  12.40  per  cent  graphite.  Southeast  of  the  shaft,  it  is 
shown  to  exist  at  least  15  feet  in  this  direction,  and  sample  No.  7 across  the  seam,  as 
shown  in  figure  22,  assays  11.73  per  cent  graphite.  The  crosscut  near  the  end  of  the 
northwest  drift  is  barren.  The  crosscut  at  the  end  of  the  southeast  drift,  however, 
though  barren  to  the  southwest,  enters  a mass  of  graphitic  material  some  10  or  15  feet 
northeast  of  the  drift  and  passes  through  25  feet  of  the  crystalline  material. 

A first  and  second  drift  on  this  ore,  as  shown  in  figure  22,  are  also  largely  on  the  ore. 
Samples  Nos.  3,  4,  and  6,  taken  in  the  drifts  and  crosscut,  contain  19.30  per  cent,  12.80 
per  cent,  and  16.36  per  cent  graphite,  respectively. 

Between  the  first  and  second  levels,  graphitic  shale  is  shown  on  the  northeast  side 
of  the  shaft ; the  balance  of  the  shaft,  however,  is  barren. 

At  the  second  level,  as  is  shown  in  short  dash  lines  in  figure  22,  there  is  a 20-foot 
drift  running  northwest.  This  drift  is  on  a 2 to  4 foot  seam  of  graphitic  shale. 
Sample  No.  2 of  this  seam  contains  13.28  per  cent  graphite.  East  of  the  shaft  a drift  has 
been  run  in  25  feet,  the  south  side  and  bottom  of  which  are  entirely  in  graphitic  shale 
containing,  according  to  sample  No.  1, 10.36  per  cent  graphite.  The  width  of  the  seam 
at  this  point  is  not,  however,  determined.  Below  the  second  level,  in  the  8-foot 
sump,  graphite  shale  appears  on  the  southwest  side,  and  sample  No.  5 shows  it  to  con- 
tain 12.50  per  cent  graphite.  The  balance  of  the  sump,  however,  including  the 
bottom,  is  barren. 

******* 

In  addition  to  this  ore  in  the  mine,  there  are  two  dumps  of  ore,  taken  from  the  work- 
ings lying  next  the  shaft.  These  I sampled  by  cutting  trenches  through  them  and 
drawing  samples  from  the  sides  of  the  trenches.  One,  an  annular  dump,  formed  to 
make  a walkway  for  the  horse-whim,  shows  by  sample  No.  11,  12.20  per  cent  graphite, 
and  contains  according  to  my  measurements  about  1,747  cubic  feet  of  loose  material, 
or,  according  to  my  determination  of  specific  gravity  (see  Laboratory  tests  et  seq.), 
80  tons. 

Another  dump,  which  I estimate  to  contain  1,800  cubic  feet,  or  89  tons,  contains, 
according  to  sample  No.  10,  10.47  per  cent  carbon. 

A third  dump,  which  shows  practically  no  value  on  its  surface,  and  which  I was 
assured  contained  only  waste  from  the  barren  portion  of  the  workings,  also  contained 
about  1,800  cubic  feet,  but  was  not  sampled. 

To  sum  up,  allowing  for  inevitable  inaccuracies,  there  are  in  sight  on  the  property 

at  least  5,500  tons  of  12  per  cent  graphite  ore. 

******* 

As  the  value  of  graphite  in  commerce  depends  not  only  on  the  percentage  of  the  pure 
mineral  present,  but  also  on  the  physical  qualities  of  this  mineral,  together  with  the 
composition  of  the  impurities  present,  and  as  the  value  of  graphite,  in  common  with 
that  of  any  ore,  also  depends  on  the  economy  with  which  a marketable  product  can 
be  produced,  I have  undertaken  a number  of  laboratory  tests  on  the  samples  which  I 
secured  with  a view  to  securing  some  indication  of  these  points. 


GRAPHITE. 


81 


A brief  description  of  these  tests  and  their  results  is  as  follows: 

A general  sample  was  made  up  of  all  the  samples  secured  underground,  and  crushed 
to  pass  a 10-mesh  sieve.  It  was  assayed  and  found  to  contain  14.50  per  cent  graphite. 
A portion  was  separated  into  various  sizes  and  carefully  examined.  Flakes  of  graphite 
being  noted,  a series  of  tests  were  undertaken  to  determine  the  amount  and  quality 
of  this  material.  Flaked  graphite  is  largely  used  in  the  manufacture  of  crucibles  and 
receives  the  highest  price  of  any  grade.  In  order  to  be  classed  as  such,  however,  the 
flakes  must  be  sufficiently  large  not  to  pass  through  a 60-mesh  sieve.  Accordingly,  in 
making  this  set  of  tests,  finer  material  than  60  mesh  was  first  carefully  screened  out  of 
weighed  portions  of  the  general  sanjple,  and  the  balance  was  washed  on  a vanning 
plaque. 

These  tests  indicate  that  ore  containing  14.50  per  cent  carbon  (the  assay  of  the  made- 
up  general  sample)  will  yield  from  1 per  cent  to  4 per  cent  of  its  weight  of  flaked 
graphite  containing  from  56  per  cent  to  40  per  cent  carbon,  whose  impurities  contain 
less  than  2 per  cent  each  of  iron  (Fe)  and  lime  (CaO) — the  most  common  of  the 
objectionable  impurities  for  crucible  manufacture. 

After  taking  out  the  flaked  graphite,  the  residues  were  crushed  to  pass  the  60-mesh 
screen,  and  added  to  the  fines  which  had  originally  passed  through  it.  These  were 
then  also  washed  on  a vanning  plaque,  and  results  were  produced  indicating  that  fine 
graphite  could  be  produced  amounting  to  from  27  per  cent  to  28  per  cent  of  the  original 
ore  and  containing  from  29.75  per  cent  to  25.80  per  cent  pure  graphite,  the  total 
recovery  of  graphite  in  the  form  of  flake  and  fines  being  60  per  cent  to  61  per  cent  of 
the  total  graphite  in  the  original  sample. 

Another  series  of  tests  of  a similar  nature  was  then  made  on  a selected  specimen  of 
the  ore  representing  a class  which  I am  inclined  to  think  could  readily  be  secured  on 
a practical  scale  by  hand  sorting.  This  specimen  contained  the  graphite  in  nodules 
of  more  or  less  pure  mineral  and  showed,  on  assay,  21  per  cent  carbon.  It  was  found 
to  contain  practically  no  value  in  flake  graphite,  but  yielded  a product  amounting  to 
31  per  cent  of  the  original,  containing  37  per  cent  carbon.  This  represents  a recovery 
of  55  per  cent  carbon  in  the  specimen. 

A third  set  of  tests  was  then  made  on  a specimen  of  the  graphite  shale,  which  also 
could  be  very  readily  secured  in  practice  by  itself.  This  was  found,  on  assay,  to  con- 
tain 16  per  cent  carbon,  and  yielded  on  vanning  no  flake,  but  a product  representing 
55  per  cent  of  the  whole,  containing  24  per  cent  carbon.  This  represented  a total 
recovery  of  81  per  cent  of  the  carbon  present  in  the  original. 

A fourth  series  of  tests  were  made  on  the  sample  taken  from  the  Lyman  lot,  which 
it  will  be  recalled  contained  15.27  per  cent  carbon.  It  yielded  1.44  per  cent  of  the 
original  as  flake  graphite  containing  42.40  per  cent  carbon,  and  21.8  per  cent  of  fine 
material  containing  40.40  per  cent  carbon.  This  represented  a recovery  of  61.6  per 
cent  of  the  carbon  present  in  the  original. 

Experiments  were  also  made  to  determine  the  effect  of  bolting  the  fine  product  of 
vanning  through  200-mesh  bolting  cloth,  the  vanned,  graphitic  material  having  first 
all  passed  100  mesh.  Before  bolting  the  sample  contained  25.80  per  cent  pure  graph- 
ite. Twenty-two  per  cent  of  this  material  failed  to  pass  through  the  200-mesh  bolting 
cloth,  and  was  found  to  contain  41.30  per  cent  carbon.  The  balance  was  either  passed 
through  or  lost  in  extremely  fine  dust  and  in  the  mesh  of  the  cloth. 

In  order  to  estimate  the  tonnage  of  ore  in  the  dumps  at  the  shaft  collar,  a series  of 
determinations  of  the  specific  gravity  of  the  well-packed  crushed  ore  was  made.  The 
average  of  these  on  sample  No.  11  of  the  annular  dump  is  1.482.  Of  sample  No.  10, 
the  other  ore  dump,  1 .591 . This  gives  a factor  of  21 .6  cubic  feet  per  ton  of  2,000  pounds 
for  the  former  and  20.2  cubic  feet  per  ton  for  the  latter. 

74625° — Bull.  450—11 6 


82  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

To  determine  the  tons  of  ore  in  sight  underground  a series  of  specific  gravity  tests 
were  made  on  some  of  the  specimens  of  the  various  classes  of  ore.  The  averages  of 


these  determinations  are  as  follows: 

Specimen  No.  1 2.  488 

Specimen  No.  2 2.  448 

Specimen  No.  3 2.  598 


Average  specific  gravity 2.  511 


This  gives  a factor  of  12.8  cubic  feet  per  ton  of  2,000  pounds. 

When  it  is  understood  that  much  of  the  territory  included  in  this 
property  has  not  been  adequately  tested  by  surface  cuts,  it  may  be 
seen  from  these  extracts  that  possibilities  exist  for  the  successful 
establishment  of  a graphite  industry  at  this  point. 

About  2 miles  south  of  Llano  graphite  schists  trending  in  a north- 
west-southeast direction  toward  Sharp  Mountain  may  be  observed. 
This  vicinity  is,  perhaps,  with  the  exception  of  the  property  just 
described,  the  most  favorable  locality  to  prospect,  though  graphite 
schists  do  occur  at  many  other  localities  throughout  the  region.  It 
must  be  borne  in  mind,  however,  in  estimating  the  graphite  content 
of  a given  band  of  schist  that  a little  graphite  makes  a very  striking 
showing. 

The  graphite  bands  are  confined  entirely  to  the  areas  mapped  as 
Packsaddle  schist. 

MANGANESE. 

Five  miles  north  of  Llano,  on  the  southeast  flank  of  Horse  Moun- 
tain, prospecting  has  been  done  on  what  is  known  as  the  Griffy  man- 
ganese deposit.  The  schists  and  gneisses  at  this  point  strike  N.  11° 
W.  and  dip  24°  SW.  Two  pits  are  opened  at  this  locality;  the  south- 
ern one  is  15  feet  long  on  the  strike  and  12  feet  wide  on  the  dip. 
About  2 feet  of  manganese  oxide  is  exposed  in  this  pit.  Quartz  is 
banded  with  the  ore.  About  90  feet  north  on  the  strike  a second  pit 
reveals  much  leaner  material. 

Both  north  and  south  from  these  pits  at  intervals  small  showings 
of  oxide  and  silicate  may  be  seen.  An  examination  of  the  pits  shows 
clearly  that  the  oxide  present  is  a decomposition  product  formed 
from  the  silicates,  which  are  observed  in  place.  Both  spessartite  (a 
manganese  garnet)  and  piedmontite  (a  manganese  epidote)  may  be 
found  in  considerable  abundance.  They  are  associated  with  quartz 
and  feldspar  in  grains,  forming  layers  and  probably  represent  meta- 
morphic  equivalents  of  the  original  elements  in  the  sediments.  A 
microscopic  examination  of  a specimen  showed  spessartite  garnet 
intergrown  with  epidote  accompanied  by  much  muscovite  and 
quartz  and  some  magnetite.  Decomposition  in  this  vicinity  is  very 
shallow,  and  below  the  oxidized  zone  the  deposits,  because  of  the  sili- 
cate nature  of  the  minerals  and  their  discontinuity  and  leanness,  are 
without  commercial  value. 


RARE-EARTH  METALS. 


83 


An  analysis  of  the  Horse  Mountain  ore,  from  a report  of  the  Arkan- 
sas Geological  Survey  in  1890,  by  R.  A.  F.  Penrose,  jr.,  is  given  below: 

Analysis  of  manganese  ore , Horse  Mountain , Llano  County,  Tex.a 


Manganese 24.  60 

Iron 3.  22 

Silica 35.93 

Phosphorus , None. 

Lime 8.  48 


In  Mason  County  manganese  occurs  in  somewhat  the  same  manner 
as  at  Horse  Mountain  and  has  been  described  in  the  report  quoted. 

RARE-EARTH  METALS. 

The  Llano  region  was  visited  by  Frank  L.  Hess  in  1907  b for  the 
purpose  of  studying  the  rare-earth  minerals,  and  the  following  notes 
are  quoted  from  his  report: 

GENERAL  DESCRIPTION  OF  THE  DEPOSIT. 

Baringer  Hill  is  located  about  100  miles  northwest  of  Austin,  Tex.,  on  the  west 
bank  of  Colorado  River,  near  the  western  edge  of  the  Burnet  quadrangle  as  mapped 
by  the  United  States  Geological  Survey.  It  is  12  miles  north  of  Kingsland,  the  near- 
est railroad  point,  16  miles  west  of  Burnet,  and  22  miles  northeast  of  the  town  of  Llano. 
It  is  a low  mound  rising  above  the  flood  plain  of  the  Colorado  and  formed  by  the  resist- 
ance to  erosion  of  a pegmatite  dike  intruded  in  a porphyritic  granite. 

Few  if  any  other  deposits  in  the  world,  and  certainly  no  other  in  America,  outside 
of  the  monazite  localities,  have  yielded  such  amounts  of  the  rare-earth  metal  minerals 
as  Baringer  Hill. 

The  writer  visited  this  region  in  the  latter  part  of  February,  1907,  fortunately  at  a 
time  when  Mr.  William  E.  Hidden,  who  has  been  largely  instrumental  in  making  this 
locality  famous  through  his  contributions  to  mineralogical  literature  on  the  rare  min- 
erals found  here,  was  conducting  mining  operations. 

The  hill  is  named  for  John  Baringer,  who  discovered  in  it  large  amounts  of  gadolinite 
about  1887.  No  one  in  the  neighborhood  knew  what  the  mineral  was,  and  specimens 
were  sent  to  a number  of  places  before  it  was  identified.  A piece  fell  into  the  hands  of 
Mr.  Hidden,  who  at  once  looked  up  the  deposit  and  afterwards  obtained  possession  of 
the  property.  Meanwhile  Mr.  Baringer  had  taken  out  a quantity  of  gadolinite  esti- 
mated at  800  to  1,200  pounds,  which  was  largely  picked  up  and  carried  off  by  persons 
in  the  neighborhood  as  curiosities.  Some  of  the  choicer  pieces,  showing  crystal  form, 
found  their  way  into  various  museums.  The  property  is  now  controlled  by  the 
Nernst  Lamp  Company,  of  Pittsburg,  Pa.,  and  is  worked  by  that  concern  for  yttria 
minerals.  Since  its  acquirement  by  this  company  a considerable  amount  of  work  has 
been  done  on  the  deposit,  consisting  mostly  of  open  cuts  around  the  edge  of  the  pegma- 
tite, reaching  a depth  of  30  or  40  feet.  A large  block,  30  feet  in  height  and  more  in 
diameter,  consisting  mostly  of  quartz,  is  left  standing  in  the  middle. 

# *****  * 

Baringer  Hill  * * * is  a small  mound  which,  before  mining  was  begun,  rose, 
perhaps,  40  feet  above  a surrounding  flat,  was  about  100  feet  wide,  and  from  200  to  250 
feet  long.  The  longer  axis  runs  east  and  west  and  is  nearly  at  right  angles  to  the 
course  of  the  Colorado  River  at  this  point.  The  country  rock  is  a coarse  porphyritic 

a Penrose,  R.  A.  F.,  jr.,  Manganese:  Ann.  Rept.  Ark.  Geol.  Survey  for  1890,  vol.  1, 1891,  p.  447, 

b Minerals  of  the  rare-earth  metals  at  Baringer  Hill,  Llano  County,  Tex.:  Bull.  U.  S.  Geol.  Survey  No. 
340,  1908,  pp.  286-294. 


84  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


granite  with  feldspar  phenocrysts  about  1 inch  long.  This  granite  seems  to  weather 
and  erode  rather  easily,  and  the  river  has  cut  a flood  plain  perhaps  one-fourth  of  a 
mile  wide  at  this  point,  while  the  dike,  owing  to  its  greater  hardness  and  freshness, 
has  better  withstood  the  erosion.  The  pegmatite,  an  unsymmetrical  body  with 
irregular  walls,  is  intruded  into  the  granite  in  what  seems  to  be  a pipe  or  short  dike. 

At  the  edges  of  the  intrusion  is  a graphic  granite  of  peculiar  beauty  and  definite 
structure,  being  more  like  the  textbook  illustrations  than  the  usual  graphic  granite 
found  in  the  field.  The  altered  band  is  from  1 foot  to  5 or  6 feet  thick  and  apparently 
surrounds  the  pegmatite.  No  segregation  of  the  feldspar  or  quartz  in  particular  parts 
of  the  dike  can  be  noted,  except  that  the  feldspar  may  possibly  be  more  inclined  to 
occupy  the  sides  of  the  intrusion.  As  far  as  shown  it  occupies  most  of  the  western  and 
southern  sides,  and  the  quartz  occupies  the  center  and  much  of  the  eastern  side. 

One  quartz  mass  is  more  than  40  feet  across.  The  quartz  has  distinct  white  bands, 
from  one-eighth  to  one-half  inch  wide,  which  seem  to  be  due  to  a movement  akin  to 
flowage  and  are  similar  to  those  found  in  many  pegmatitic  masses  in  other  portions  of 
the  country.  The  white  banding  is  due  to  small  liquid  inclusions,  many  of  them 
containing  bubbles  which  either  do  not  move  from  change  of  inclination  of  the  frag- 
ment containing  them,  or  do  so  but  slowly.  The  cavities  are  minute,  largely  of  irreg- 
ular, angular  shapes,  suggesting  at  first  glance  particles  of  broken  minerals,  and  occur 
in  straight  or  broken  lines  that  probably  follow  fine  cracks  which  were  later  cemented. 
Groups  of  these  cracks,  with  their  inclusions,  form  the  bands,  which  seem  to  lie 
approximately  parallel  to  the  walls  of  the  dike  or  at  such  angles  with  them  as  might 
easily  be  formed  by  the  flowage  of  the  material  into  the  space  it  occupied  in  the 
granite.  The  condition  of  the  quartz  seems  to  show  that  the  pegmatite,  after  being 
forced  into  the  granite,  partly  cooled  and  solidified  and  then  made  another  small 
movement,  or  a series  of  slight  movements,  at  which  time  the  minute  fractures  were 
formed  in  the  quartz  and  the  magmatic  fluids  were  forced  into  them,  but  as  the  mass 
was  not  yet  totally  solidified  the  cracks  were  effectually  healed  and  the  fluid  was 
inclosed.  Such  movements  may  be  supposed  to  have  been  consequent  on  the  read- 
justment of  the  mass  on  cooling.  Between  the  fracture  bands  the  quartz  is  glassy  and 
clear.  At  one  place  a vug  was  found  large  enough  for  a man  to  enter,  lined  with 
“smoky”  quartz  crystals  reaching  1,000  pounds  or  more  in  weight.  This  would  seem 
to  indicate  that  the  pegmatite  had  been  intruded  in  a pasty  or  semifluid  condition 
and  that  the  vugs  represent  the  spaces  occupied  by  segregated  water  that  was  squeezed 
from  the  magma  as  the  minerals  took  their  final  solidified  form. 

The  feldspar  is  an  intergrowth  of  microcline  and  albite,  of  a brownish  flesh  color, 
beautifully  fresh,  and  occurs  (1)  in  large  masses  reaching  over  30  feet  in  diameter,  and 
(2)  as  huge  crystals,  many  of  which,  though  they  rarely  show  terminal  planes,  have 
one  or  more  sharply  defined  edges,  especially  where  partially  surrounded  by  quartz. 
An  edge  34  inches  long  was  measured  on  one  crystal  thus  embedded . A smaller  crystal 
was  seen  which  was  about  a foot  long,  weighed  perhaps  20  pounds,  and  showed  fine 
terminations  and  twinning  planes. 

A large  amount  of  feldspar  has  been  mined  and  thrown  on  the  dump,  and  it  is 
possible  that  in  time  the  dump  material  may  be  utilized,  either  for  its  potassium 
content,  as  a fertilizer,  or  for  pottery  making. 

Large  crystals  of  fluorspar,  measuring  a foot  along  the  edge,  occur  in  the  quartz,  but 
this  mineral  does  not  form  any  considerable  percentage  of  the  mass.  The  fluorspar 
ranges  from  almost  colorless  to  violet  so  dark  that  it  is  practically  opaque.  Where 
found  alone  in  the  quartz  it  was,  so  far  as  observed,  of  lighter  color  than  where  found 
with  dark-colored  minerals.  Mr.  Hidden  informed  the  writer  that  it  sometimes 
becomes  luminous  at  the  temperature  of  a living  room. 

Ilmenite  occurs  in  radiating  bunches  of  sheets  or  blades  ranging  from  1 inch  to  10 
or  11  inches  in  width  and  from  one-sixteenth  to  one-fourth  of  an  inch  in  thickness. 
In  cross  section  the  ilmenite  looks  like  the  ribs  of  a fan,  with  the  outer  ends  from  one- 


KAKE-EAKTH  METALS. 


85 


fourth  to  three-fourths  of  an  inch  apart.  Similar  aggregations  take  different  angles, 
and  numbers  of  such  groups  are  found  lying  close  together.  With  them  occurs  biotite 
mica  in  like  bunches,  the  sheets  of  which  are  said  to  reach  3 feet  in  width  by  an  inch 
in  thickness.  The  mica  is  reported  by  Mr.  Hidden  to  contain  caesium  and  rubidium, 
and  to  be  close  to  lepidomelane  in  constitution.  Small  flakes  of  lithia  mica  reaching 
half  an  inch  in  diameter  are  found,  generally  along  cracks  in  the  quartz.  No  musco- 
vite was  seen,  but.it  is  said  to  be  found  occasionally.  Compared  with  the  mass  the 
total  amount  of  mica  is  very  small. 

THE  RARE-EARTH  MINERALS. 

The  greatest  interest  in  the  dike  centers  in  the  accessory  minerals,  particularly  in 
the  occurrence  of  the  rare-earth  metal  minerals,  which,  as  stated,  probably  have  never 
been  found  at  any  other  place  in  such  large  masses  and  in  such  quantities  as  in  this 
locality.  So  far  the  excavations  are  comparatively  shallow,  and  such  minerals  as  are 
found  are  more  or  less  weathered.  Many  show  their  crystalline  form,  but  owing  to 
alteration  the  crystals  are  now  imperfect. 

Allanite,  a variable  silicate  of  calcium,  iron,  aluminum,  the  cerium  metals  (cerium, 
praseodymium,  neodymium,  and  lanthanum),  and  in  smaller  amount  those  of  the 
yttrium  group,  occurs  in  large  masses,  one  of  which  weighed  300  pounds  and  was 
embedded  in  purple  fluorspar.  It  is  a dense  black  mineral  with  a fine  luster,  and  a 
hardness  of  about  6.  Around  the  edges  and  along  cracks  it  shows  alteration  to  a brown 
substance  having  a hardness  of  about  5.5.  The  percentage  of  yttria  ordinarily  occur- 
ring in  allanite  is  small  and  rarely  exceeds  2\  per  cent. 

Cyrtolite  is  rather  common  in  the  dike  in  peculiarly  fine,  polysynthetic  groupings 
with  curved  faces.  It  is  brown  on  the  surface,  with  a darker  or  nearly  black  interior, 
and  is  evidently  a mixture  of  substances.  It  carries  a considerable  amount  of  zirconia 
and  some  yttria,  and  is  supposed  by  Mr.  Hidden  to  be  an  alteration  product  of  zircon. 
If  it  is  such  a derivative,  the  original  mineral  was  probably  much  more  complicated 
than  ordinary  zircon.  It  makes  a fair  radiograph,  which  also  gives  evidence  of  its 
nonhomogeneity . 

Fergusonite,  a variable  columbate  of  the  yttrium  group  and  other  of  the  rare-earth 
metals,  occurs  in  four  varieties,  so  different  as  to  be  almost  distinct  minerals.  The 
difference  between  them  is  due  to  oxidation  and  hydration.  No  anhydrous  varieties 
are  found.  It  is  found  in  crystalline  form  surrounded  by  decomposition  zones. 
Bunches  of  irregular  crystals  have  been  broken  out,  weighing  over  65  pounds.  It  is 
generally  a mixture  of  minerals,  as  may  be  easily  seen  on  a smooth  surface  from  the 
different  colors.  The  difference  in  composition  is  strikingly  shown  in  a radiograph, 
the  variations  being  marked  by  difference  in  radiation.  According  to  the  two  analyses 
by  Hidden  and  Mackintosh, a the  fergusonite  obtained  here  carries  from  31.36  to  42.33 
per  cent  of  yttria  and  accompanying  rare-earth  metals,  and  42.79  to  46.27  per  cent  of 
columbium  dioxide.  The  two  analyses  give  1.54  per  cent  and  7.05  per  cent  of  uranium 
oxides.  These  are  probably  very  irregularly  distributed  through  the  material,  as 
shown  both  by  the  mineral  itself  and  especially  by  its  radiographs,  which  are  of  striking 
beauty. 

Gadolinite,  a silicate  of  beryllium,  iron,  and  yttrium,  is  the  most  important  of  the 
minerals  found  here.  It  contains  about  42  per  cent  of  the  yttrium  oxides,  with  a 
molecular  weight  of  260,  and  occurs  in  crystals  and  masses  of  irregular  shape  up  to 
200  pounds  in  weight.  The  outer  portion  of  the  mineral  and  that  adjacent  to  the 
cracks  is  altered  to  dense  brick-red  material,  but  the  mineral  itself  is  of  a fine,  glassy 
black,  with  a smooth  conchoidal  fracture.  Thin  splinters  are  bottle-green  in  color. 


a Hidden,  W.  E.,  and  Mackintosh,  J.  B.,  Yttria  and  thoria  minerals  from  Llano  County,  Tex.:  Am.  Jour. 
Sci.,  3d  ser.,  vol.  38,  1889,  pp.  483-484.  The  minerals  of  this  locality  have  been  well  described  by  these 
writers  in  a number  of  papers. 


86 


MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


It  has  a specific  gravity  of  a little  over  4.2  and  a hardness  of  6.5  to  7.  A specimen 
collected  makes  no  impression  on  a photographic  plate  with  50  hours’  exposure. 

Polycrase,  a columbate  and  titanate  of  yttrium,  erbium,  cerium,  and  uranium,  occurs 
in  grains,  small  masses,  and  plates,  the  last  associated  with  ilmenite  in  such  a manner 
as  to  suggest  the  probability  of  replacement.  It  normally  contains  between  20  and 
30  per  cent  of  yttrium  oxide,  but  is  in  too  small  amount  to  be  commercially  important. 
It  is  very  radioactive  and  quickly  affects  a photographic  plate. 

Other  rare-earth  metal  minerals  found  in  the  dike  are  yttrialite,  rowlandite,  nivenite, 
gummite  of  several  varieties,  thorogummite,  mackintoshite,  and  tengerite.  These 
minerals  are  apt  to  occur  in  any  part  of  the  dike,  either  in  the  quartz  or  the  feldspar, 
but  have  so  far  been  found  mostly  along  the  outer  portions.  A peculiarity  of  their 
occurrence  is  that  they  are  found  in  bunches  from  which,  if  in  quartz,  radial  cracks 
extend  in  every  direction,  and  by  following  such  cracks  the  minerals  are  found.  An 
illustration  of  such  an  occurrence  was  published  by  William  E.  Hidden  in  1905. a The 
cause  of  these  “stars,”  as  they  have  been  called  by  Mr.  Hidden,  is  not  clear,  but  the 
thought  suggests  itself  that  the  rare-earth  metal  minerals  may  have  crystallized  first 
from  the  magma  and  the  solidifying  quartz,  being  unable  otherwise  to  accommodate 
itself  to  the  incompressible  nucleus  cracked  in  this  manner. 

Mr.  Hidden  stated  that  in  mining  one  of  the  largest  pockets  the  faces  and  hands  of 
himself  and  his  assistant  were  affected  as  if  by  sunburn,  and,  as  in  sunburn,  the  covered, 
flesh  was  not  irritated.  He  suggested  radioactivity  as  the  cause,  and  inasmuch  as 
the  minerals  under  consideration  are  radioactive,  the  explanation  seems  plausible.  & 
The  following  was  given  by  Mr.  Hidden  in  a personal  communication  as  a complete 
list  of  the  minerals  found  in  Baringer  Hill : 

Minerals  found  in  Baringer  Hill,  Llano  County , Tex. 

Silicates. 

Microcline  •}  occur  as  intergrowths  making  up  the  mass  of  the  feldspar. 

Allanite;  a variable  silicate  of  calcium,  iron,  the  cerium  metals,  and  less  amounts  of 
the  yttrium  group,  in  masses  weighing  up  to  300  pounds,  embedded  in  purple 
fluorspar. 

Biotite;  close  to  lepidomelane. 

Cyrtolite;  hydrated  silicate  of  zirconium,  yttrium,  and  cerium.  Radioactive, 
abundant. 

Gadolinite;  a silicate  of  beryllium,  iron,  and  yttrium  in  masses  weighing  up  to  200 
pounds. 

Lithia  mica;  apparently  a later  deposition  in  cracks  in  quartz.  Small  flakes  one-half 
inch  or  less  across. 

Orthoclase;  not  abundant. 

Yttrialite;  an  anhydrous  silicate  of  thoria,  yttrium,  and  cerium  earths.  Contains 
about  30  per  cent  silica,  46  per  cent  yttria,  10  to  12  per  cent  thoria,  and  5 to  6 per 
cent  ceria.  Does  not  occur  in  large  quantity. 

Rowlandite;  practically  a hydrated  yttrium  silicate.  Contains  5 per  cent  fluorine. 

Columbates. 

Fergusonite;  four  varieties,  due  to  oxidation  and  hydration.  Neither  is  anhydrous. 
Purest,  5.65  specific  gravity.  So  different  as  to  be  almost  distinct  minerals.  Crys- 
tals surrounded  by  decomposition  zones. 

Polycrase;  columbate  and  titanate  of  yttrium,  erbium,  cerium,  and  uranium.  Con- 
tains about  25  per  cent  of  yttria. 


a Some  results  of  late  mineral  research  in  Llano  County,  Tex.:  Am.  Jour.  Sci.,  4th  ser.,  vol.  19,  1905,  p.  432. 
b Mr.  Hidden  has  described  this  incident  in  the  article  referred  to. 


RARE-EARTH  METALS. 


87 


Oxides. 

Hematite;  specular,  small  quantity. 

Magnetite;  without  metallic  acids  or  rare  earths. 

Ilmenite;  iron-titanium  oxide  in  beautiful  crystals,  as  well  as  plates  up  to  8 or  9 inches 
broad . 

Rutile;  titanium  oxide,  in  prismatic  and  reticulated  forms  one-fourth  inch  thick. 
Quartz;  large  masses  and  crystals  of  white  quartz  and  “ smoky”  crystals  up  to  1,000 
pounds  in  weight.  Amethysts  of  gem  quality  reach  1 inch  by  one-half  inch. 

Uranates. 

Mackintoshite;  3 parts  thorite  to  1 part  uraninite;  contains  13  per  cent  silica  and  a 
small  amount  of  yttria.  Radioactive;  several  times  more  so  than  its  alteration 
product. 

Thorogummite ; formed  from  mackintoshite  by  addition  of  H20  and  alteration  of  U02 
to  U03. 

Nivenite;  a uranate  of  uranium,  thorium,  yttrium,  and  lead.  Contains  10  per  cent 
of  lead.  The  most  soluble  uranate  yet  discovered;  soluble  in  5 per  cent  solution 
of  S03.  Prints  well  and  gives  great  detail.  Occurs  in  cubes  and  masses.  (See 
Dana’s  System  of  Mineralogy,  p.  889,  for  two  analyses.)  Alters  to  gummite. 
Gummite;  several  varieties. 

Phosphate. 

Autunite;  hydrous  phosphate  of  uranium  and  calcium;  secondary,  not  analyzed. 

Carbonates. 

Tengerite;'  carbonate  of  yttrium  and  beryllium.  Generally  globular,  but  occurs  also 
as  crystals  up  to  one-sixteenth  inch  in  length  singly  and  as  little  nests.  May  be 
a mixture  of  beryllium  and  yttrium  carbonates. 

Lanthanite;  carbonate  of  lanthanum,  containing  also  cerium,  praseodymium,  and 
calcium.  In  incrustations  on  allanite. 

Sulphides. 

Chalcopyrite;  iron-copper  sulphide,  massive,  in  small  amount. 

Pyrite;  iron  sulphide,  cubic  and  octahedral. 

Sphalerite;  zinc  sulphide;  the  purest  fergusonite  contains  some  zinc. 

Molybdenite;  molybdenum  sulphide  in  scales  5 inches  wide,  which  form  masses 
weighing  up  to  10^  pounds.  Alters  to  powellite. 

Molybdate. 

Powellite;  calcium  molybdate,  in  white  crusts  lining  cavities  where  MbS  has  been. 
Sugary  white  radiating  or  plumose  crystals,  one-fourth  to  three-fourths  inch  long. 
Locally  greenish. 

It  is  interesting  to  note  that  among  the  numerous  minerals  in  this  dike  no  tourmaline, 
zircon,  beryl,  monazite,  cassiterite,  garnet,  or  tungsten  minerals,  have  been  found. 
Cassiterite  has  been  reported  from  the  neighborhood,  but  its  occurrence  is  extremely 
doubtful. 

With  the  exception  of  the  alteration  products  and  probably  of  the  lithia  mica,  which 
as  noted,  occurs  along  cracks  in  the  quartz,  all  the  minerals  are  believed  to  be  original 
constituents  of  the  dike. 

The  possibility  of  finding  dikes  having  a like  variety  of  minerals  at  once  suggests 
itself,  and  much  prospecting  has  been  done  for  them.  A few  specimens  of  the  rare- 
earth  metal  minerals  have  been  found  at  other  places  in  the  neighborhood,  but  only  a 
few,  and  in  small  quantity.  However,  similar  dikes  occur,  as  already  stated,  and 
these  have  not  all  been  thoroughly  investigated.  It  is  to  be  remembered  that  these 


88  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


minerals  form  but  a small  fraction  of  1 per  cent  of  the  mass,  and  it  might  easily  happen 
that  comparatively  large  amounts  could  exist  in  a dike  and  not  be  exposed  at  the  out- 
crop. They  are  minerals  which  are  altered  to  softer  products  by  exposure,  and  would 
thus  be  easily  removed  by  erosion  and  weathering.  The  cracks  surrounding  nuclei  of 
the  minerals  should  be  useful  in  prospecting. 

ECONOMIC  VALUE. 

The  economic  interest  in  the  rare-earth  metal  minerals  centers  in  their  incan- 
descence on  being  heated,  and  owing  to  this  property  they  have  been  much  sought. 
Thoria,  beryllia,  yttria,  and  zirconia  show  it  in  the  greatest  degree.  It  was  found, 
however,  that  thoria  and  beryllia,  which  form  the  bulk  of  the  incandescent  oxides 
used  in  gas  mantles,  are  too  easily  volatilized  to  be  used  in  an  electric  glower,  such  as 
that  of  the  Nernst  lamp.  Yttria  and  zirconia,  however,  will  stand  the  necessary  high 
temperature.  Up  to  the  discovery  of  this  deposit  it  was  practically  impossible  to  get 
sufficient  yttria-bearing  minerals  to  manufacture  the  lamps,  but  fergusonite  and 
gadolinite,  with  lesser  amounts  of  cyrtolite,  are  found  here  in  large  enough  quantity  to 
meet  the  requirements.  The  zirconia  is  obtained  from  zircon  brought  from  other 
localities. 

In  the  manufacture  of  the  glowers  for  the  Nernst  lamp,  a paste  consisting  of  25  per 
cent  of  yttria  and  75  per  cent  of  zirconia  is  squirted  into  strips  of  the  proper  thickness, 
baked,  and  cut  into  the  required  lengths.  When  cold  the  mixture  is  nonconducting, 
but  after  being  heated  it  becomes  a conductor  and  gives  a brilliant  light. 

The  needs  of  the  Nernst  Lamp  Co.,  which  owns  the  deposit,  require  only  the  occa- 
sional working  of  the  mine.  After  enough  yttria  minerals  are  obtained  to  supply  its 
wants  for  a few  months  ahead,  the  mine  is  closed.  But  a few  hundred  pounds  per  year 
are  extracted. 

Rare-earth  minerals  have  been  noted  at  several  localities  besides 
Baringer  Hill. 

Professor  Hidden  mentions  the  discovery  of  two  crystals  of  gadolin- 
ite about  a mile  south  of  Baringer  Hill.  Several  pounds  of  allanite 
were  taken  from  a mass  of  pegmatite  outcropping  as  a low  knoll 
about  2b  miles  west-northwest  from  Kingsland,  near  Williams’s  garden. 
Fluorite  occurs  with  the  allanite  at  this  place.  The  amount  of 
prospecting  is  practically  negligible. 

In  Burnet  County,  2 miles  due  east  of  Baringer  Hill  and  about  one- 
half  mile  west  of  Shiloh  Church,  is  another  gadolinite  locality.  The 
matrix  rock  is  like  the  pegmatite  of  Baringer  Hill,  but  the  mass  is 
obviously  smaller.  The  old  workings  consist  of  a shallow  trench 
from  which  a few  tons  of  pegmatite  have  been  removed. 

All  the  above-mentioned  localities  are  in  the  area  of  coarse  red 
granite.  Outside  of  the  granite  area  only  one  locality  came  under 
observation.  Near  the  east  side  of  Mr.  Dorbant’s  pasture,  south  of 
the  Burnet-Bluffton  road,  small  masses  of  weathered  rare-earth 
minerals  are  to  be  found  in  irregular  narrow  dikes  of  pegmatite 
inclosed  in  dark  schists.  This  locality  is  about  4 1 miles  from  Colo- 
rado River  and  7 miles  from  Burnet. 


MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS.  89 

ZINC  BLENDE  WITH  FLUORITE  GANGUE. 

Deposits  of  fluorite  carrying  irregular  amounts  of  metallic  sulphide 
minerals  occur  at  two  localities  west  of  Burnet  within  the  drainage 
basin  of  Spring  Creek.  A fluorite-bearing  reef  has  been  opened  on 
the  Bailey  place,  about  4 miles  from  Burnet  and  a mile  west  of  the 
Bluffton  road.  In  this  vicinity  the  rocks  are  pre-Cambrian  gneisses 
and  schists  cut  by  minor  masses  of  granite  and  pegmatite.  Struc- 
tural trends  are  east  and  west,  the  rocks,  though  poorly  exposed, 
being  evidently  complexly  folded.  The  outcrop  of  the  fluorite  reef 
is  on  top  of  a ridge  between  two  of  the  upper  tributaries  of  Spring 
Creek.  The  bulk  of  the  rocks  adjacent  are  feldspathic  gneisses,  but 
with  these  are  interlay ered  masses  of  hornblende  schist.  Locally  the 
strike  of  the  different  layers  is  about  N.  60°  E.,  and  dips  are  to  the 
southeast. 

A mixture  of  fluorite  and  hornblende  with  a little  quartz,  feldspar, 
and  chalcopyrite  occurs  in  the  form  of  a layer  inclosed  by  light- 
colored  gneiss.  The  material  carries  scattered  grains  of  galena. 

The  deposit  was  prospected  several  years  ago  by  means  of  a shaft 
and  nine  shallow  excavations.  A line  joining  the  several  openings 
trends  N.  60°  E.  From  what  could  be  made  out  in  1909,  it  appears  that 
fluorite  was  found  along  the  strike  of  the  layer  for  a distance  of  nearly 
300  feet.  On  the  southwest  the  mineral  was  encountered  in  five 
trenches,  showing  an  extent  along  the  reef  of  100  feet.  Counting 
toward  the  northeast,  trench  No.  5 shows  a bunch  of  mineral  which 
seems  to  represent  the  bottom  of  a shallow  trough,  as  gneiss  is 
exposed  on  both  sides  and  below  it.  The  next  trench  lies  135  feet 
northeast  of  No.  5.  Here  there  is  no  evidence  of  the  reef  and  the 
intervening  ground  is  completely  covered.  However,  about  40  feet 
farther  on  is  the  shaft,  about  which  is  piled  a considerable  amount 
of  fluorite  rock.  This  shaft  contains  water  within  about  20  feet  of 
the  surface.  Its  lower  portion  is  evidently  in  feldspathic  gneiss. 

About  15  feet  northeast  of  the  shaft  is  a pit  sufficiently  deep  to 
expose  20  feet  of  the  fluorite-bearing  layer  measured  down  the  dip, 
the  dip  being  less  than  10°  SE.  Thirty  feet  beyond,  another  excava- 
tion appears  to  have  revealed  no  mineral,  and  the  same  is  true  of  a 
long  trench  325  feet  northeast  of  the  shaft.  All  the  fluorite  from 
this  locality  is  white. 

The  purest  masses  of  the  mineral  appear  in  the  southwesterly  pits, 
where  the  reef  averages  perhaps  less  than  a foot  in  thickness.  In  the 
part  adjacent  to  the  shaft  on  the  northeast,  the  reef  has  a maximum 
thickness  of  2J  feet,  but  pinches  and  swells  to  a marked  degree. 
Here  the  fluorite  constitutes  about  60  per  cent  by  bulk  of  a granular 
rock  containing  hornblende,  quartz,  feldspar,  and  a little  chalcopyrite. 
A carefully  taken  sample  of  the  fluorite  rock  piled  up  about  the 
shaft  showed  on  assay  a trace  of  gold  and  0.38  ounce  silver.  Copper 


90  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

was  not  determined,  but  from  the  small  amount  of  chalcopyrite  in 
the  fluorite  rock  this  metal  can  hardly  amount  to  more  than  1 per 
cent. 

Fluorite  accompanied  by  zinc  blende  is  found  at  several  points  in 
the  upper  valley  of  the  north  fork  of  Spring  Creek  on  and  near  the 
Frank  Thomas  place.  The  locality  is  about  7 miles  west  of  Burnet. 
The  occurrence  of  the  mineral  is  in  layers  conforming  with  the  north 
and  south  trending  structure  of  the  inclosing  dark  hornblende 
schists.  About  half  a mile  north  of  the  dwelling  house  a shaft  has 
been  opened  to  a depth  of  25  feet.  Here  the  layer  or  reef  is  about 
3^  feet  thick  at  the  outcrop.  The  material  thrown  out  of  the  shaft 
is  a mixture  of  fluorite  sulphide  minerals  and  a little  quartz.  Zinc 
blende  is  the  most  abundant  metallic  mineral,  but  galena,  pyrite, 
and  molybdenite  may  be  observed.  The  assay  of  a carefully  taken 
sample  of  the  material  thrown  out  of  the  shaft  shows0  zinc  7.60 
per  cent;  lead,  none;  gold,  a trace;  silver,  0.56  ounce. 

Whether  or  not  this  reef  has  any  degree  of  continuity  along  the 
strike  can  not  be  stated,  since  no  adequate  surface  explorations  have 
been  made.  In  the  absence  of  any  assurance  of  a continuous  vein 
no  estimate  of  the  prospective  value  of  this  deposit  is  warranted. 
It  may  be  said,  however,  that  if  only  a few  thousand  tons  of  7 per 
cent  zinc  ore  could  be  developed  there  is  no  apparent  reason  against 
the  possibility  of  profitable  mining  upon  a small  scale. 

In  the  vicinity  of  the  Thomas  dwelling  house  fluorite  has  been  dis- 
covered near  the  well  on  the  east  of  the  creek  bed.  The  reef,  which 
is  not  over  10  inches  wide,  trends  north  and  south  and  stands  nearly 
vertical.  Going  south  along  the  strike  the  mineral  has  been  uncov- 
ered in  three  or  four  places  within  a distance  of  somewhat  more  than 
one-fourth  mile.  At  one  point  a shaft  sunk  in  black  schist  encoun- 
tered fluorite  and  chalcopyrite  disseminated  in  black  hornblende 
schist. 

Other  outcrops  of  fluorite  were  seen  south  of  the  eastward-flowing 
drain  one-half  mile  south  of  the  house. 

Some  of  the  fluorite  in  this  vicinity  is  nearly  free  from  other  miner- 
als, but  specimens  may  be  found  which  are  made  up  of  nearly  equal 
parts  of  black  zinc  blende  and  fluorite,  with  a little  quartz  and  a 
little  pyrite.  Such  prospecting  as  has  been  done  is  not  sufficient  to 
demonstrate  that  these  deposits  have  any  promising  degree  of 
persistence. 

SERPENTINE  AND  TALC. 

Talc  deposits  have  been  found  at  a number  of  places  within  the 
pre-Cambrian  rocks  and  serpentine  has  been  found  in  a body  of 
considerable  size  at  one  locality.  Prospecting  has  been  carried  on 
with  a view  to  proving  commercial  deposits  at  several  places. 


Assay  by  E.  E.  Burlingame. 


SERPENTINE  AND  TALC. 


91 


Serpentine. — The  Collins  property,  located  9 miles  south  of  Llano, 
a little  west  of  the  Oxford  road,  contains  about  250  acres  lying  in  a 
strip  about  1^  miles  long  in  a north-south  direction.  Near  the  north 
end  of  the  property  and  on  a hillside  is  a pit  perhaps  20  feet  in  diam- 
eter and  10  feet  deep.  This  pit  is  in  serpentine  and  exposes  on  its 
west  side  a contact  with  soapstone.  For  perhaps  100  feet  east  and 
northeast  of  this  pit  and  for  at  least  500  feet  southeast  and  south  ser- 
pentine is  exposed. 

At  the  foot  of  the  hill  a second  pit  about  30  feet  in  diameter  by 
10  or  15  feet  deep  exposes  serpentine  rock.  At  this  point  a diamond- 
drill  hole  was  bored  275  feet  deep  without  passing  out  of  serpentine 
rock.  Over  the  next  pass  to  the  south,  serpentine  is  exposed  for  100 
feet  or  more  down  the  slope,  and  a third  pit  about  10  feet  wide  by 
20  feet  long  and  10  feet  deep  has  been  opened.  Except  a small  out- 
crop of  schist,  the  pit  exposes  only  serpentine. 

To  the  west  and  also  partly  surrounding  these  exposures  of  serpen- 
tine are  very  considerable  exposures  of  soapstone,  in  which  occur 
veinlets  of  asbestos  and  geodes  of  quartz  and  amethyst  crystals. 

It  may  be  seen  from  the  dimensions  given  above  that  a consider- 
able deposit  of  serpentine  and  talc  exists  at  this  locality.  Specimens 
were  seen  which  took  a fine  polish.  The  commercial  value  of  such 
a deposit  will  depend  directly  upon  the  demand  that  can  be  created 
for  the  serpentine. 

Though  blasting  has  been  the  only  method  employed  in  taking 
out  material,  blocks  of  considerable  size  have  been  extracted,  and 
if  more  refined  methods  are  used,  there  is  no  doubt  that  much  larger 
blocks  would  be  quarried  and  sawn  into  commercial  sizes.  An 
installment  to  carry  on  such  work  on  a large  scale  would  involve  a 
considerable  investment,  and  the  opening  of  the  property  on  a small 
scale  would  seem  for  the  present  more  advisable.  Market  condi- 
tions and  transportation  would  need  to  be  carefully  considered  before 
any  extensive  plan  of  operation  were  adopted. 

The  relation  of  the  outcrop  of  the  body  above  described  to  the 
inclosing  schist-gneiss  series  leaves  little  doubt  that  the  deposit  is 
an  alteration  product  of  a pyroxenic  or  peridotitic  intrusive  mass. 
As  has  been  shown  in  an  earlier  portion  of  this  report  gabbroic  and 
dioritic  types  of  intrusives  are  present  in  the  region.  The  presence 
of  quartz  and  amethyst  geodes  and  the  occurrence  of  iron  oxides  in 
connection  with  the  deposit  point  to  the  same  conclusion;  that  is, 
they  represent  the  silica  and  iron  content  derived  from  the  breaking 
down  of  magnesian  iron  silicate  minerals. 

Talc. — Talc  is  found  at  a number  of  localities  in  addition  to  that 
associated  with  the  serpentine  deposit  already  described.  In  the 
area  immediately  east  of  Cedar  Mountain,  numerous  small  outcrops 
were  seen,  though  in  no  case  was  any  deposit  mapped  separately. 


92  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

A small  deposit  also  occurs  1J  miles  west  of  Llano,  and  a deposit  on 
which  considerable  work  has  been  done  is  located  about  1 mile 
north  of  Graphite  station. 

The  small  deposit  west  of  Llano  is  formed  without  doubt  by  the 
hydration  of  magnesian  silicate  minerals  developed  by  regional  or 
contact  metamorphism  in  pre-Cambrian  limestone  strata.  A small  pit 
is  opened  on  the  ledge,  but  stripping  has  been  insufficient  to  prove 
the  horizontal  extent  of  the  body.  The  presence  of  silicate  minerals 
in  the  talc  would  destroy  its  commercial  value.  This  point  can 
only  be  determined  by  exploration  work.  Locally  silicate  minerals 
were  noted  in  the  material. 

The  talc  deposits  east  of  Cedar  Mountain  are  associated  with  the 
dark  series  of  schists  described  earlier  in  this  report.  This  locality, 
however,  is  exceptional  in  that  considerable  bodies  of  dioritic  rocks 
are  intruded  into  the  schist  series.  The  talc  in  this  area  is  probably 
in  a large  measure  derived  from  limestones  by  the  hydration  of 
magnesian  silicate  minerals.  It  is  almost  certain,  however,  that 
some  of  the  deposits  are  due  to  the  alteration  of  basic  intrusives  or 
their  equivalents,  the  amphibole  schists.  No  large  deposits  of  talc 
were  seen  in  this  vicinity,  but  considering  the  soft  nature  of  talc 
and  its  tendency  to  break  down  and  be  covered  up  by  surface  soil, 
it  is  suggested  Jdiat  prospecting  might  reveal  commercial  deposits. 

Surface  outcrops  do  not  give  much  information  as  to  underground 
conditions  at  the  property  located  a mile  north  of  Graphite  station. 
The  following  notes  regarding  underground  developments  are  ab- 
stracted from  a private  report  by  William  Young  Westervelt,  to  whom 
part  of  the  underground  workings  were  accessible.  The  open  cut  de- 
scribed was  poorly  exposed  at  the  time  of  the  present  writer’s  visit. 

The  property  contains  in  all  some  980  acres  and  the  openings  are  all 
within  a few  hundred  feet  of  the  Houston  & Texas  Central  Railroad. 
The  workings  are  along  a general  northwest-southeast  course  and 
consist,  commencing  at  the  southeast  end,  of  the  following  openings: 
A small  shaft  has  been  sunk  28  feet,  from  the  bottom  of  which  two 
crosscuts  have  been  driven  in  northeast  and  southwest  directions. 
At  the  time  of  visit  the  northeast  crosscut  was  13  feet  from  the  center 
of  the  shaft.  The  southwest  crosscut  was  too  nearly  filled  to  be 
accessible,  though  it  was  stated  to  be  9 feet  long  from  the  center  of 
the  shaft  and,  like  the  northeast  drift,  all  in  soapstone.  The  shaft 
itself  was  noted  to  be  entirely  in  soapstone. 

At  33  feet  northwest  of  the  shaft  is  an  open  crosscut  14  feet  wide, 
14  feet  deep  at  one  end,  and  sloping  up  in  a northeasterly  direction  to 
a depth  of  but  a foot  or  so  at  its  northeast  end,  40  feet  distant.  At  the 
southwest  end  a schist  wall  is  exposed,  but  for  a distance  of  about  25 
feet  from  the  wall  the  cut  is  made  entirely  in  soapstone.  This  soap- 
stone in  the  deepest  part  exhibits  considerable  solidity,  and  appar- 
ently blocks  of  some  size  could  be  taken  from  it. 


OIL. 


93 


At  83  feet  northwest  of  the  first  shaft  is  a second  shaft  32  feet  deep, 
but  it  was  inaccessible.  The  dump  consists  entirely  of  soapstone, 
and  it  is  probable  that  the  shaft  is  wholly  in  that  material.  From 
the  workings  described  there  is  good  evidence  that  a mass  of  soap- 
stone 20  feet  wide  by  90  feet  long  by  25  feet  deep  is  present.  The 
horizontal  extent  of  this  body  can  only  be  determined  by  more  cross- 
cuts and  shafts,  the  outcrop  being  hidden  by  the  surface  mantle 
of  soil. 

The  successful  introduction  of  this  material  into  the  market  will 
depend,  first,  on  the  size  of  the  deposit  that  can  be  proved  to  exist,  and 
second,  on  whether  or  not  the  several  physical  characteristics  are 
present  which  are  necessary  in  such  material  to  permit  competition 
with  quarries  operating  in  the  East. 

There  is  very  little  doubt  that  the  deposit  owes  its  origin  to  the 
hydration  of  magnesian  silicate  minerals  developed  in  pre-Cambrian 
limestone  by  metamorphism.  Such  an  origin  would  give  to  the 
deposit  a bedlike  character  continuous  in  depth  and  horizontal  extent 
only  in  so  far  as  the  silicate  minerals  had  been  developed  and  later 
altered  to  talc.  As  this  process  might  result  in  deposits  of  great 
extent  or  in  podlike  masses  of  small  size,  it  follows  that  exploration 
by  crosscuts  and  shafts  is  the  only  practical  method  of  exploring  the 
deposit. 

OIL. 

A small  oil  seepage  in  a spring  near  the  town  of  Burnet  has  deposited 
at  the  surface  asphaltic  material  in  the  cracks  and  interstices  of  the 
neighboring  limestones.  In  Post  Mountain,  also,  a little  oily  residue 
is  found  about  20  feet  above  the  base  of  the  Cretaceous.  The  beds  in 
which  this  oily  residue  is  found  are  very  near  the  base  of  the  Creta- 
ceous system,  and  consequently  only  a few  feet  above  the  underlying 
Paleozoic  beds.  (See  geologic  map,  PI.  III.) 

The  underlying  Cambro-Ordovician  limestones,  shales,  and  sand- 
stones have  not  shown  any  indication  of  oil  throughout  the  Llano- 
Burnet  region.  The  Carboniferous  strata  of  the  region,  on  the  other 
hand,  have  a decidedly  petroliferous  odor.  Though  the  Trinity 
sand  at  Burnet  is  deposited  on  Cambro-Ordovician  limestone,  it  is 
quite  possible  that  a short  distance  to  the  east  Carboniferous  beds, 
raised  by  faulting,  may  be  the  basement  upon  which  the  Cretaceous 
sands  rest.  It  is  possible  therefore  that  oil  has  passed  from  the 
underlying  Carboniferous  into  the  porous  Trinity  sand  and  spread 
laterally  as  far  west  as  Burnet. 

As  has  been  pointed  out  by  Taff  and  Reed,a  the  Trinity  sand  is  of 
such  character  (being  a beach  or  shallow-water  deposit  of  siliceous 

a Taff,  J.  A.,  and  Reed,  W.J.,  The  Madill  oil  pool,  Oklahoma:  Bull.  U.  S.  Geol.  Survey  No.  381,  1910, 
p.  513. 


94  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

sand  with  thin  beds  of  clay)  as  almost  to  preclude  the  idea  that  oil 
originated  in  that  formation. 

The  lack  of  other  indications  of  oil  in  other  portions  of  the  Trinity 
in  this  region,  the  structurally  broken  and  eroded  condition  of  the 
underlying  Paleozoic,  and  the  petroliferous  odor  of  the  Carboniferous 
beds  point  to  the  conclusion  that  though  a small  quantity  of  oil  may 
have  passed  upward  from  below,  it  is  extremely  improbable  that  oil 
in  commercial  quantities  is  present  in  the  Burnet  and  Llano  quad- 
rangles. 

STRUCTURAL  MATERIALS. 

Limestone,  sandstone,  and  granite  are  present  in  large  quantities 
in  the  central  Texas  region,  and  in  the  pre-Cambrian  schist  series 
marbleized  limestone  beds  also  are  found. 

MARBLE. 

Only  a few  attempts  have  been  made  to  utilize  the  marbleized 
limestone  beds  occurring  in  the  pre-Cambrian  rocks.  A small  amount 
was  quarried  from  an  opening  near  Bachelor  Peak  and  was  used  in 
part  in  the  construction  of  the  Llano  courthouse.  Recently  an  open- 
ing has  been  made  by  Messrs.  Sellman  and  Bernard,  of  Llano,  on  a 
marble  ledge  on  the  northern  edge  of  the  town  of  Llano.  The  oper- 
ators propose  to  work  the  deposit,  at  least  at  first,  on  a small  scale  to 
supply  a local  demand  for  such  material. 

It  may  be  said  in  general  that  much  of  -the  marble  in  the  pre- 
Cambrian  is  of  slight  value  because  of  its  impurities.  It  is  not  im- 
probable, however,  that  ledges  exist  of  sufficient  width  and  length 
and  of  such  color  and  purity  that  quarry  floors  could  be  successfully 
opened.  Such  localities  can  only  be  found  by  diligent  search,  with 
careful  sampling  by  surface  cuts  or  pits. 

The  marble  is  practically  all  of  a fairly  coarse  crystalline  type,  more 
or  less  mottled  blue  or  black.  Some  pure  white  ledges  undoubtedly 
occur,  but,  taken  as  a whole,  the  material  represents  a common  variety 
of  stone  and  probably  will  never  command  a high  price.  That  oper- 
ations may  be  carried  on  at  a fair  profit,  however,  at  some  time  in  the 
future  is  probable. 

SANDSTONE. 

A sandstone  quarry  has  been  operated  intermittently  for  a number 
of  years  at  a point  north  of  Fairland,  Burnet  County.  A consider- 
able quantity  of  this  material  has  been  shipped  out  of  the  county, 
and  the  stone  is  used  also  in  neighboring  towns.  The  quarry  is 
opened  in  beds  of  the  Hickory  sandstone.  At  this  point  the  mate- 
rial is  a light  brown,  rather  fine-grained  sandstone.  The  beds  dip 
gently  into  the  hillside,  and  bedding  planes  are  prominent  and  add 


STRUCTURAL  MATERIALS. 


95 


to  the  ease  with  which  the  stone  may  be  worked.  A spur  connects 
the  quarry  with  the  Houston  & Texas  Central  Railroad.  The 
demand  fo"  this  stone  at  the  present  time  is  limited,  competing  as  it 
must  with  abundant  limestone  building  material  at  points  beyond 
the  Llano-Burnet  region. 

LIMESTONE. 

Portions  of  the  Edwards  limestone  and  certain  layers  in  the  Trinity 
formation  can  be  used  for  building  purposes.  The  latter  beds,  of 
yellowish  to  white  color,  are  quite  easily  extracted  and  in  the  quarry 
are  often  so  soft  that  they  may  be  sawed  into  blocks.  This  material 
becomes  harder  when  exposed  to  the  air. 

GRANITE. 

Granite  forms  a considerable  proportion  of  the  pre-Cambrian  rock 
of  the  region.  Unfortunately,  however,  from  the  viewpoint  of  the 
quarryman,  all  of  this  material  is  not  available  for  use.  In  an  earlier 
part  of  this  report  it  was  shown  how  the  intrusion  of  granite  had 
locally  produced  areas  characterized  by  the  presence  of  abundant 
schist  fragments  intermixed  with  the  intruding  rock.  The  condi- 
tion is  a very  common  and  unfortunate  one,  and  if  it  were  not  that 
many  extensive  areas  also  are  underlain  by  clean  stone  the  quarry 
industry  in  this  region  could  have  only  a decidedly  moderate  growth. 
It  may  be  said  at  once,  however,  that  granting  transportation  and 
market,  there  is  available  an  enormous  quantity  of  clean  granite  in 
the  region. 

Of  this  material  two  very  distinct  types  are  present — (1)  the  coarse 
and  very  coarsegrained  granites  and  (2)  the  medium  to  finegrained 
granites,  among  which  & number  of  varieties  may  be  distinguished. 

Of  these  two  types  the  former  is  commonly  free  from  such  imper- 
fections as  would  prevent  its  use,  while  the  latter  is  locally  marred 
or  spoiled  by  the  presence  of  schist  fragments  or  iron  pyrite. 

By  a glance  at  the  map  (PI.  Ill,  in  pocket)  it  may  be  seen  that  an 
extensive  area  of  very  coarse  grained  rock  underlies  the  territory  in 
southwest  Llano  County.  Practically  inexhaustible  supplies  of  this 
granite  lie  above  what  would  be  railroad  grade  in  the  vicinity  of 
Enchanted  Rock.  A further  examination  will  show  that  both  at 
Granite  Mountain  in  Burnet  County  and  north  of  that  point  are 
broad  areas  underlaid  by  coarse-grained  stone.  The  wide  distribu- 
tion of  the  fine-grained  types  may  also  be  seen,  but  of  them  it  is  not 
possible  to  predict  that  any  given  spot  consists  of  clean  granite,  for, 
as  explained  above,  various  impurities  may  be  present.  In  such 
areas  only  by  careful  examination  can  excellent  quarry  sites  be 
selected.  ~ 

A number  of  quarries  have  been  opened  in  areas  more  or  less 
characterized  by  the  presence  of  schist  fragments,  and  at  other 


96  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 


localities  abandoned  quarries  were  seen  where  the  presence  of  iron 
pyrite  must  have  been  one  of  the  factors  leading  to  their  disuse. 

One  fact  directly  dependent  upon  the  geologic  relation  of  the 
granite  to  the  schists  and  having  a decidedly  practical  bearing  on 
the  selection  of  quarry  sites  is  this:  In  areas  of  mixed  schist  and 
granite  (that  is,  where  granite  has  intruded  the  schists  in  a compli- 
cated way)  there  can  be  no  assurance  that  what  is  apparently  an 
excellent  quarry  floor  will  hold  its  valuable  qualities  in  depth.  It  is 
in  fact  probable  that  schist  fragments  will  be  encountered  in  such 
amount  as  either  wholly  to  ruin  the  enterprise  or  to  reduce  profits  to 
a minimum.  It  is  of  course  true  that  the  mass  may  continue  clean, 
but  the  chance  is  too  small  to  be  worth  the  risk. 

At  the  present  time  transportation  facilities  deeply  affect  the 
growth  of  the  granite  industry,  the  Parkinson  group  of  quarries,  for 
example,  being  so  situated  that  a wagon  haul  of  6 miles  is  necessary. 
The  haul  for  other  quarries  is  as  much  as  11  miles.  A number  of 
quarries,  however,  have  been  operated  near  the  railroad,  the  quarry 
at  Granite  Mountain  (the  most  extensive  operation  in  the  region), 
on  the  Houston  & Texas  Central  Railroad  being  a notable  example. 

At  the  present  time,  exclusive  of  that  from  the  Granite  Mountain 
quarry,  by  far  the  greater  part  of  the  stone  quarried  is  used  for 
monumental  purposes.  The  stone,  for  example,  from  the  Gootch  & 
Wells  quarry,  on  the  Parkinson  tract,  and  from  the  Norton  quarry, 
11  miles  south  of  Llano,  is  a medium  to  fine  grained  gray  granite,  and 
takes  a fine  polish.  Much  of  the  granite  is  well  suited  for  large 
structures  and  could  be  so  utilized  were  transportation  better  and  a 
more  active  market  available. 

Granite  Mountain  quarry. — The  Granite  Mountain  quarry  is  located 
on  the  Houston  & Texas  Central  Railroad  at  Granite  Mountain, 
Burnet  County,  near  the  town  of  Marble  Falls.  The  owners  since 
1893  are  Darragli  & Catterson.  Before  that  date  the  property  was 
owned  by  Lacey,  Westfall  & Norton. 

The  quarry  is  opened  in  the  side  of  a broad,  low,  bare,  granite  hill. 
No  stripping  is  necessary.  Sufficient  granite  is  exposed  above  the 
present  railroad  grade  to  furnish  material  for  a great  many  years. 

The  rock  is  coarse-grained  pink  granite,  consisting  of  quartz,  mi- 
crocline  (dominant),  albite-oligoclase,  some  orthoclase,  and  biotite. 
Though  portions  of  the  mass  are  intruded  with  pegmatite,  an  enor- 
mous quantity  of  fine  material  is  at  hand.  A well-defined  rift  aids 
quarrying.  Sheets  of  any  desirable  thickness  can  be  lifted,  and  facil- 
ities for  handling  impose  the  only  limit  to  the  size  of  blocks  that  may 
be  obtained.  The  greater  part  of  the  rock  quarried  has  been  shipped 
in  5 to  10  ton  blocks  to  the  Galveston  jetty.  This  work  was  begun 
in  1891  and  continued  to  1898.  Little  work  was  done  from  1898  to 
1902  From  1902  to  the  present  time  about  1,000,000  tons  of  rock 


STRUCTURAL  MATERIALS. 


97 


were  shipped.  Before  that,  however,  2,000,000  tons  were  shipped, 
and  in  addition  120,000  yards  of  crushed  rock  have  been  used  on  the 
same  work..  Probably  2,000,000  tons  were  used  as  cap  rock. 

The  capitol  building  at  Austin,  begun  in  1884  and  finished  in  1899, 
and  courthouses  in  Galveston,  Houston,  and  at  other  localities,  are- 
built  of  this  granite.  Nevertheless,  but  a small  part  of  the  output 
has  been  dimension  stone.  This  class  of  stone  will  probably  grow  in 
importance. 

The  quarry  is  equipped  with  20-ton  rigging.  There  are  5 derricks, 
a 1,500-foot  cableway,  and  a tram.  The  rock  is  generally  swung 
direct  to  the  cars.  A No.  7J  Gates  crusher  is  also  installed.  About 
two-thirds  of  the  labor  employed  is  white.  Engineers  are  paid  $2.50 
to  $3.50  per  day;  derrick  men,  $2.75  to  $3;  foremen,  $4;  common 
laborers,  $1.50  to  $1.75. 

Freight  rates  per  ton  of  rough  granite  to  points  in  Texas  range,  from 
$1  to  San  Antonio  to  $1.40  to  Aransas  Pass. 

TeicJi  quarry  No.  2. — This  quarry  is  a short  distance  west  of  Kings- 
land,  Llano  County,  and  is  connected  by  a spur  with  the  Houston 
& Texas  Central  Railroad.  It  is  owned  by  Mr.  Frank  Teicli,  of 
Llano,  and  was  opened  in  1908.  The  rock  is  a coarse-grained  pink 
granite,  and  takes  a fine  polish.  The  Memorial  Church  of  Orange, 
Tex.,  is  built  of  this  rock.  About  50,000  cubic  feet  have  been  ex- 
tracted, valued  at  50  cents  a cubic  foot.  The  quarry  was  not  being 
worked  when  it  was  visited. 

Mr.  Teich  operated  a small  quarry  on  the  Parkinson  tract  6 miles 
south  of  Llano  during  the  summer  of  1909.  About  6,000  cubic  feefe 
was  extracted  and  manufactured  into  monuments  at  Teich’s  polish- 
ing works  near  Llano.  This  quarry  was  abandoned  in  the  summer  of 
1910.  A new  quarry,  Teich  No.  3,  is  being  opened  about  4 miles 
south  of  Llano  on  Mr.  Sheeon’s  land. 

Gootch  cfe  Wells  quarry. — Gootch  & Wells  are  operating  a quarry 
on  the  Parkinson  tract  about  6 miles  south  of  Llano.  The  quarry 
presents  a very  rough  and  irregular  appearance.  The  pit  is  from  25 
to  50  feet  deep  and  about  150  long  in  an  east-west  direction.  About 
100  feet  wide  at  the  east  end,  it  narrows  to  15  or  20  feet  at  the  west 
end.  The  rock  lies  in  somewhat  irregular  sheets  broken  by  vertical 
joints.  N.  50°  E.  is  the  easiest  break. 

The  following  section  will  give  an  idea  of  the  sheeting: 

Section  showing  sheeting  in  Gootch  <$c  Wells  quarry,  Llano  County,  Tex . 


Feet. 

Top  ledge,  not  used  (low  dip  northwest) 5-10 

Rotten  granite 1-  2 

Thick  ledge 12  ± 

Rotten  seam \ 

Ledge 8 

Ledge 4 

74625°— Bull.  450—11 7 


98  MINERAL  RESOURCES  OF  LLANO-BURNET  REGION,  TEXAS. 

The  thickness  of  the  sheets  varies  considerably,  and  the  presence 
in  parts  of  the  quarry  of  pegmatite  and  schist  inclusions  spoils  much 
rock.  The  stone  is  a beautiful  gray  granite,  somewhat  resembling 
the  Barre,  Vt.,  stone.  It  consists  of  quartz,  microcline  feldspar  with 
a little  albite-oligoclase  and  orthoclase  feldspar.  Biotite  in  small 
flakes  is  the  dark  mineral.  The  quarries  are  equipped  with  4 der- 
ricks, gasoline  engines,  and  5 air  drills.  Plug  and  feathers  are  largely 
used  for  breaking  on  the  finish  work.  The  quarry  can  produce  250 
cubic  feet  per  day. 

The  granite  is  hauled  to  the  Houston  & Texas  Central  Railroad 
at  Llano  in  wagons  at  a cost  of  15  cents  per  cubic  foot.  Freight  on 
rough  stock  varies  from  50  cents  to  $2.50  per  ton  within  the  State 
limits.  From  Llano  to  Houston  the  rate  is  $1.45.  The  entire 
product  of  the  quarry  is  used  for  monumental  work.  The  actual 
cost  of  quarrying  is  about  40  cents  a cubic  foot,  varying  with  the 
nature  of  the  seams  in  the  quarry.  The  rough  stone  is  sold  from  the 
quarry.  Dressing  costs  from  $1  to  $25  per  cubic  foot,  according 
to  the  nature  of  the  designs. 

The  best  quality  of  stock  sells  for  $1.50  a cubic  foot,  this  grade 
being  used  for  best  polished  work.  The  cheapest  stock  used  for 
hammered  work  sells  for  90  cents  per  cubic  foot. 

The  quarry  produced  during  1908  about  18,000  cubic  feet  and  will 
produce  during  1909  about  22,000  feet.  The  entire  Parkinson  tract 
produced  during  1908  (including  quarries  operated  by  Messrs.  Pat- 
terson, Blodgett,  Leiter,  and  Teich)  about  33,000  feet. 

Norton  quarry. — The  Norton  quarry,  owned  by  Mr.  Norton,  of 
Llano,  is  located  about  11 J miles  southwest  of  Llano  and  about  3J 
miles  a little  east  of  south  of  Sixmile  post  office.  The  quarry  pit  is 
nearly  rectangular  and  measures  95  feet  long  in  a north  and  south 
direction.  It  is  about  35  feet  wide  and  12  to  15  feet  deep.  Natural 
walls,  caused  by  small  north  and  south  seams,  make  the  west  and 
east  sides.  The  north  end,  trending  N.  60°  E.,  is  a very  straight 
break.  The  rock  breaks  easiest  the  “capping  way,”  while  north- 
south  and  east- west  breaks  are  about  the  same  in  this  respect.  The 
stone  is  a bluish-gray,  fine-grained  granite  composed  essentially  of 
quartz,  and  microcline  feldspar,  with  a little  albite-oligoclase  and 
orthoclase.  The  dark  mineral  is  biotite  mica  in  fine  flakes.  A little 
chlorite  is  present.  Pyrite  was  noted,  occupying  almost  invisible 
seams;  it  is  not  abundant,  however,  though  some  fine  blocks  are 
spoiled  by  its  presence.  Schist  fragments  also  spoil  some  of  the  rock. 
The  plant  includes  2 derricks  and  a horse  winze. 

Stewart  quarry. — E.  L.  Stewart,  in  August,  1908,  opened  a new 
quarry  near  the  old  Stewart  quarry,  about  10J  miles  southwest  of 
Llano  and  about  2\  miles  a little  west  of  south  of  Sixmile  post  office. 


STRU CTTJRAL  MATERIALS. 


99 


The  rock  is  a fine-grained  gray  granite.  Pyrite  is  very  abundant  in 
parts  of  the  old  Stewart  quarry  near  by  and  may  also  interfere  with 
the  new  opening.  Schistose  material  is  included  in  much  of  the 
granite  of  the  vicinity  and  this  fact,  combined  with  the  presence  of 
pyrite  and  the  long  haul  to  the  railroad  will  probably  prevent  exten- 
sive developments.  Two  carloads  have  been  shipped  to  San  Antonio 
and  Paris  markets,  principally  for  monumental  purposes.  The  rock 
is  hauled  for  25  cents  a cubic  foot  loaded  at  quarry  and  unloaded  at 
Llano.  Quarrymen  receive  from  $2  to  $2.50  per  day. 

Other  quarries. — Mr.  Bradshaw  has  opened  a small  quarry  one- 
fourth  of  a mile  west  of  the  Gootch  & Wells  quarry.  Only  the  top 
rock  has  been  removed  over  a small  area. 

Mr.  H.  P.  Bailey  is  also  opening  a quarry  three-fourths  of  a mile 
north  of  Bradshaw’s.  Only  a few  cubic  feet  of  rock  have  been 
quarried. 

Mr.  George  Patterson  is  operating  a quarry  on  the  Parkinson  tract 
south  of  Llano,  but  no  notes  are  at  hand  covering  the  operations. 

A number  of  quarries  have  been  worked  in  the  past,  but  are,  for 
the  present  at  least,  abandoned.  Such  are  the  Town  Park  quarry 
north  of  Llano,  where  pyrite  marred  a very  beautiful  coarse-grained 
gray  granite  porphyry;  the  Kansas  City  quarry,  2 miles  west  of  Llano 
on  the  Mason  road,  and  the  quarry  7 miles  northwest  of  Burnet, 
where  a very  dark  gray,  slightly  gneissoid  granite  has  been  quarried. 


INDEX. 


A. 

Page. 


Acknowledgments  to  those  aiding 7 

Algonkian  rockS  (?),  character,  subdivisions, 

and  distribution  of 9-22 

Allanite,  character  of 85 

B. 

Bader  incline,  iron  ore  from,  analysis  of. ....  59 

Bader  tract,  deposits  at 31-34 

iron  ore  from,  analyses  of 34 

character  of 33 

record  of  drill  hole  at 33 

workings  at  map  showing 32 

Badu,  N.  J.,  assistance  of 7,29 

Bancroft,  Howland,  work  of 7 

Baringer  Hill,  deposits  at 81-88 

geological  structure  of 84-85 

minerals  of 86-87 

rare-earth  minerals  of 85-88 

Basic  intrusive  rocks,  character  and  distribu- 
tion of 21-23 

Bay  ley,  W.  S.,  work  of 7 

Beaver  Creek,  folding  of  sandstone  at,  plate 

showing 76 

Beck,  R.,  on  Russian  iron  ores 68 

Bluff  ton,  lead  prospects  near 76-77 

lead  prospects  north  of,  map  showing  re-  75 
lations  of  Upper  Cambrian  and  pre- 
Cambrian  granite  hear,  figure 

showing 76 

Burnet  quadrangle,  map  showing 8 


C. 


Cambrian  rocks,  character  and  subdivisions  of  23-24 
Cambro-Ordovician  rocks,  character  and  dis- 
tribution of 24 

Carboniferous  rocks,  character  and  subdi- 
visions of 24-25 

Castell,  iron  deposits  near •. 42-48 

Cedar  Mountain,  diorite  from 22 

Clements,  J.  Morgan,  on  contact  effect 64 

Click,  intrusive  rock  from 22 

pyrite  deposits  near,  distribution  of,  figure 

showing 54 

Coal  Creek,  intrusive  rock  from 22 

Copper,  distribution  and  ores  of 73-74 

Cyrtolite,  character  of 85 

D. 

Dabney,  J.  B.,  on  Olive  mine  iron  ore 29 

Deep  Creek  prospects,  distribution  and  char- 
acter of 42-44 

iron  ore  of,  character  of 43 

map  showing 43 

Drainage  system  of  the  region 8-9 


E. 

Page. 

Elm  Creek  prospects,  distribution  and  char- 
acter of 45-48 

iron  ore  of,  analyses  of 46, 48 

character  of 46,48 

maps  showing 45,47 

Erosion,  relation  to  faulting,  figure  showing  . 37 

Esbon,  granite  from 13 

F. 

Faulting,  relation  to  folding  and  erosion,  fig- 
ures showing 36,37 

Feldspar  of  Baringer  Hill,  character  of 84 

Fergusonite,  varieties  of 85 

Flowage  of  schist,  plate  showing 10 

Fluorite,  distribution  and  character  of 89-90 

Fluorspar  of  Baringer  Hill,  character  of 84 

Folding,  of  sandstone,  plate  showing 10 

relation  to  faulting  and  erosion,  figures 

showing 36,37 

G. 

Gabbro-diorite  intrusives,  character  and  dis- 
tribution of 21-23 

Gadolinite,  character  of 85 

Galena,  distribution  and  origin  of 76-77 

Geology  of  the  region 9-26 

Gneisses  and  schists,  divisions  and  distribu- 
tion of 14-21 

origin  of 20-21 

Gold,  assays  and  distribution  of 70-73 

prospect  for,  map  showing 72 

Goldmine  Creek,  intrusive  rock  from 22 

Goodes  Spring,  granite  from 13 

Goodwin  iron  prospect,  character  of  ore  at. . . 41 

Gootch  & Wells  quarry,  granite  of 97-98 

section  of 97 

Granite,  character  and  subdivisions  of.  10-14, 95-99 

dis  tribution  of 11, 95-99 

geologic  relations  of 10-11 

intruding  schist,  plate  showing 76 

local  character  of,  at — 

Esbon 13 

Gootch  & Wells  quarry 97-98 

Granite  Mountain  quarry 96-97 

Grays  Mountain 13 

Kansas  City  quarry 12 

Kings  Mountain 13 

Heine’s  well 13 

Hog  Mountain 12 

Norton  quarry 13,98 

Parkinson  quarry T. . 12 

Stewart  quarry 98-99 

Teich  quarry •. 97 

Granite  Mountain  quarry,  granite  of 97-98 


101 


102 


INDEX, 


Page. 

Graphite,  distribution  of 77-82 

prospect  for,  map  showing 79 

report  on 78-82 

Grays  Mountain,  granite  from 13 

H. 

H.  & G.  N.  Section  13,  iron  ore  of,  analysis 

of 53 

iron  ores  of,  character  of 50-53 

prospects  in,  map  showing 50 

relations  of  ore  layers,  figure  showing 51 

Heath  gold  prospect,  development  at 71-73 

map  showing 72 

Heines  well,  granite  from 13 

Hess,  Frank  L.,  on  rare  earths 83-88 

Hog  Mountain,  granite  from 12-13 

Horse  Mountain,  manganese  ore  from,  char- 
acter and  analysis  of 82-83 

I. 

Iddings,  J.  P.,  on  opaline  granite 14 

Igneous  rocks,  relation  of  to  origin  of  iron  ore.  60-68 
Intrusive  rocks,  character  and  distribution  of.  21-23 

Iron  Mountain,  deposits  at 34-40 

geological  structure  of 37-38 

granite  from 13 

iron  ore  of,  analyses  of 39 

character  of 35-37, 39 

record  of  drill  hole  at 39 

vertical  section  of  ore  body,  figure  show- 
ing  36 

workings  at,  map  showing 35 

Iron  ores,  character,  distribution,  and  geo- 
logical relations  of 26-70 

chemical  analyses  of 28-29, 

34, 39. 46, 48, 53, 58-59 

chemical  relations  of 62-65 

deposits  of 56-57 

local  character  and  occurrence  of 26-55 

origin  of,  consideration  of 56-70 

hypotheses  for 56 

summary  regarding 69-70 


K. 

Kansas  City  quarry,  granite  from 12 

Kay,  Fred  H.,  work  of 7 

Key ser- Jones  tract,  iron  ore  of 40-41 

prospects  on,  map  showing 40 

Kings  Mountain,  granite  from 13 

L. 

Lead,  occurrence  of 75-77 

ore,  character  of 76-77 

prospects  for,  development  of 76-77 

map  showing . 76 

Limestone,  character  and  economic  value  of.  95 

Linton,  Robert,  assistance  of 29-30 

Lively  tract,  iron  ore  of 48-49 

' ' Llanite , ’ ’ character  and  composition  of 14 

Llano  quadrangle,  maps  showing — 8;  in  pocket. 
Llano  series,  divisions  and  distribution  of — 14-21 

origin  of 20-21 

Lone  Grove,  graphite  deposit  at,  development 

of ’ 78-82 

graphite  deposit  at,  report  on 80-82 

workings  at,  map  showing 79 


M.  Page. 

Magnetite,  concentration  of,  figure  showing. . 61 

Magnetite  gneiss,  sketch  of  ore  surface  in 52 

Magnetite  ore,  banding  of,  plate  showing 10 

distribution  of,  figures  showing 40, 

43,45,47,49,50 

See  also  Iron  ores. 

Manganese,  distribution  of 82-83 

*e,  analysis  of 83 

character  of 82 

Marble,  character  of 94 

N. 

Newland,  D.  H.,  on  iron  ores 69 

Norton  quarry,  granite  from 13,98 

O. 

Oatman  Creek,  Packsaddle  schist  near,  sec- 
tion of 16 

Oil,  distribution  and  occurrence  of 93-94 

Olive  property  , development  of 28-31 

iron  ore  from,  analyses  of 28,29 

character  of 28-31 

workings,  map  showing 30 

Opaline  granite, character  and  composition  of  14 

Opaline  quartz-feldspar  porphyry,  character 

and  composition  of 14 

P 

Packsaddle  schist,  character  of 15-18 

distribution  of 15-16 

section  of 16 

Paleozoic  rocks, character  and  subdivisions  of.  23-25 

Parkhill  (iron)  prospect,  deposits  of 42 

Parkinson  quarries,  granite  from 12-13 

Penrose,  R.  A.  F.,  jr.,  analysis  by 83 

Polycrase,  character  of 86 

Q. 

Quartz  of  Baringer  Hill,  character  of 84 

R. 

Radio-activity,  indications  of,  in  rare-earth 

deposits 86 

Rare-earth  metals,  Baringer  Hill,  deposits  of.  83-88 

distribution  of 83 

economic  value  of 88 

minerals  of 86-87 

radio-activity  of 86 

Riley  Mountain,  iron  ore  of,  character  of 54-55 

Rosenbusch,  H-.,  on  contact  effect 63 

Rough  Mountain,  diorite  from 23 

S. 

! Sandstone,  character 94-95 

Schaller,  W.  T.,  analysis  of  iron  ore  by 59 

examination  of  gold  ore  by 71 

Schist,  assimilation  of  at  granite  contact,  plate 

showing 10 

flowage  of  at  granite  contact,  figure  show- 
ing  10 

fragments  of  at  granite  contacts,  figures 

showing 10, 61  ,.62 

Schists  and  gneisses,  distribution  and  sub- 
divisions of 14-21 

origin  of 20-21 

Sederholm,  J.  J.,  on  granites  of  Finland 57 

Serpentine,  character  and  distribution  of 91 

I Silver,  assays  for 70 


INDEX, 


103 


Page. 

Spencer,  A.  C.,  on  iron  ores 26 

work  of 7 

Stewart  quarry,  granite  of 98-99 

Structural  materials,  character  and  distribu- 
tion of 94-99 

Structure  of  the  region 25-26 

T. 

Talc,  distribution  of 90-93 

workings  for 92-93 

Teall,  J.  J.  H.,  on  adinole 63 

Texas,  geologic  map  o 7 

Topography  of  the  region 7, 8-9 

U. 

Upper  Cambrian  rocks,  character  and  distri- 
bution of 23 


V.  Page. 

Valley  Spring  gneiss,  character  and  distri- 
bution of 19-20 

Van  Hise,  C.  R.,  on  distribution  of  ele- 
ments  69 

on  scales 68 

W. 

W atch  Mountain,  granite  from 12 

Westervelt,  W.  Y.,  on  Lone  Grove  graphite. . 79-82 

on  occurrence  of  talc 92-93 

Wells,  R.  C.,  analyses  by 46,53 

Z. 

Zinc  blende,  character  and  occurrence  of 89-90 


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